Exhibit 99.1

FIRST QUARTER 2003

Supplemental Operating and Financial Data

This Supplemental Operating and Financial Data is not an offer to sell or solicitation to buy any securities of the Company. Any offers to sell or solicitations of the Company shall be made by means of a prospectus. The information in this Supplemental Package must be read in conjunction with, and is modified in its entirety by, the Quarterly Report on Form 10-Q (the "10-Q") filed by the Company for the same period with the Securities and Exchange Commission (the "SEC") and all of the Company's other public filings with the SEC (the "Public Filings"). In particular, the financial information contained herein is subject to and qualified by reference to the financial statements contained in the 10-Q, the footnotes thereto and the limitations set forth therein. Investors may not rely on the Supplemental Package without reference to the 10-Q and the Public Filings. Any investors' receipt of, or access to, the information contained herein is subject to this qualification.

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INDEX

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DISCLOSURE REGARDING FORWARD-LOOKING STATEMENTS

        Certain information discussed in this literature may constitute forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995 and the federal securities laws, including Section 21E of the Securities Exchange Act of 1934. The Company intends such forward-looking statements to be covered by the safe harbor provisions for forward-looking statements contained in the Private Securities Litigation Reform Act of 1995 and Section 21E of the Securities Exchange Act of 1934. Such forward-looking statements relate to, without limitation, the Company's future economic performance, plans and objectives for future operations and projections of revenue and other financial items. Forward-looking statements can be identified by the use of words such as "may," "will," "should," "expect," "anticipate," "estimate," "continue" or comparable terminology. Although the Company believes that the expectations reflected in such forward-looking statements are based upon reasonable assumptions at the time made, it can give no assurance that its expectations will be achieved. Forward-looking statements are inherently subject to certain risks, trends and uncertainties, many of which the Company cannot predict with accuracy and some of which the Company might not even anticipate. Future events and actual results, financial and otherwise, may differ materially from the results discussed in the forward-looking statements. Readers are cautioned not to place undue reliance on these forward-looking statements. Among the risks, trends and uncertainties are changes in the general economic conditions, including those affecting industries in which the Company's principal tenants compete; any failure of the general economy to recover timely from the current economic downturn; the extent of any tenant bankruptcies; the Company's ability to lease or re-lease space at current or anticipated rents; changes in the supply of and demand for office, office/flex and industrial/warehouse properties; changes in interest rate levels; changes in operating costs; the Company's ability to obtain adequate insurance, including coverage for terrorist acts; the availability of financing; and other risks associated with the development and acquisition of properties, including risks that the development may not be completed on schedule, that the tenants will not take occupancy or pay rent, or that development or operating costs may be greater than anticipated. For further information on factors which could impact the Company and the statements contained herein, reference should be made to the Company's filings with the Securities and Exchange Commission including Quarterly Reports on Form 10-Q, Current Reports on Form 8-K and Annual Reports on Form 10-K. The Company assumes no obligation to update or supplement forward-looking statements that become untrue because of subsequent events.

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I. COMPANY BACKGROUND

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I. COMPANY BACKGROUND

About the Company

        Mack-Cali Realty Corporation (NYSE: CLI) is one of the largest real estate investment trusts (REITs) in the United States with a total market capitalization of $4.0 billion at March 31, 2003. Mack-Cali has been involved in all aspects of commercial real estate development, management and ownership for over 50 years and has been a publicly-traded REIT since 1994. Mack-Cali owns or has interests in 264 properties, primarily class A office and office/flex buildings, totaling approximately 29.2 million square feet, serving as home to approximately 2,100 tenants. The properties are located primarily in suburban markets of the Northeast, many with adjacent, Company-controlled developable land sites able to accommodate up to 8.9 million square feet of additional commercial space.

History

        Established over 50 years ago, in 1994 the New Jersey-based firm became a publicly-traded company listed on the New York Stock Exchange under the ticker symbol CLI. Through combinations with some of the top companies in the real estate industry—most notably New Jersey-based Mack Company and Westchester, New York-based Robert Martin Company—Mack-Cali has become one of the leading real estate companies in the country.

Strategy

        Mack-Cali's strategy is to be a significant real estate owner and operator in its core, high-barriers-to-entry markets, primarily in the Northeast.

Summary
(as of March 31, 2003)

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Board of Directors

Executive Officers

Mitchell E. Hersh, Chief Executive Officer

Timothy M. Jones, President

Barry Lefkowitz, Executive Vice President and Chief Financial Officer

Roger W. Thomas, Executive Vice President, General Counsel and Secretary

Michael A. Grossman, Executive Vice President

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Equity Research Coverage

Company Contact Information

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II. FINANCIAL HIGHLIGHTS

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II. FINANCIAL HIGHLIGHTS

Quarterly Summary

        Funds from operations (FFO), after adjustment for straight-lining of rents, for the quarter ended March 31, 2003 amounted to $65.6 million, or $0.92 per share, versus $65.9 million, or $0.92 per share, for the quarter ended March 31, 2002. For the first quarter 2003, the Company's dividend payout ratio on FFO was 68.6 percent, as compared to 67.3 percent for the same period last year. For further discussion, see "Information About FFO and CAD" on page 11.

        Net income for the first quarter 2003 equaled $30.0 million, or $0.52 per share, versus $40.6 million, or $0.70 per share, for the same quarter last year, a per share decrease of 25.7 percent.

        Cash available for distribution (CAD) for the first quarter 2003 equaled $55.6 million versus $57.0 million for the same quarter last year. For the first quarter 2003, the Company's dividend payout ratio on CAD was 80.9 percent as compared to 77.7 percent for the same period last year. For further discussion, see "Information About FFO and CAD" on page 11.

        Total revenues for the first quarter 2003 increased 3.9 percent to $148.3 million as compared to $142.7 million for the same quarter last year.

        All per share amounts presented above are on a diluted basis; basic per share information is included in the financial tables on page 26.

        The Company had 57,592,309 shares of common stock, 7,811,830 common operating partnership units and 215,894 $1,000-face-value preferred operating partnership units outstanding as of quarter end. The outstanding preferred units are convertible into 6,230,707 common operating partnership units. Assuming conversion of all preferred units into common units, the Company had a total of 71,634,846 shares/common units outstanding at March 31, 2003.

        As of March 31, 2003, the Company had total indebtedness of approximately $1.8 billion, with a weighted average annual interest rate of 6.87 percent. Mack-Cali had a total market capitalization of $4.0 billion and a debt-to-undepreciated assets ratio of 41.0 percent at March 31, 2003. The Company had an interest coverage ratio of 3.23 times for the quarter ended March 31, 2003.

        The following is a summary of the Company's recent activity:

Property Sales

        In March, the Company sold 1770 St. James Place, a 103,689 square-foot office building located in Houston, Harris County, Texas, for approximately $5.8 million.

        Additionally, in April, Stadium Gateway, a 273,194 square-foot class A office building in Anaheim, California was sold for approximately $52.5 million. A joint venture of the Company and Highridge Partners held a 65 percent interest in the property.

Financing Activity

        In March, the Company completed three transactions with the Teachers Insurance and Annuity Association (TIAA), as follows:

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Issued one million eight-percent cumulative perpetual preferred depository shares with a liquidation value of $25 per depository share for a total of $25 million. The shares are callable at par after five years.



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Repurchased $25 million in existing 7.18 percent unsecured notes, due to mature on December 31,2003, for $26.1 million.

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•

Exchanged $25 million in existing 7.18 percent unsecured notes, due to mature on December 31, 2003, for $26.1 million in 5.82 percent unsecured notes that mature on March 15, 2013. The coupon on the new bonds was agreed to on February 5, 2003 at 182.5 basis points above the 10-year treasury on that date and were priced to yield 6.40 percent.

        In March, the Company's Board of Directors declared a cash dividend of $0.63 per common share (indicating an annual rate of $2.52 per common share) for the first quarter 2003, which was paid on April 21, 2003 to shareholders of record on April 3, 2003.

        In accordance with the Company's Share Repurchase Program, during the first quarter 2003, the Company purchased 35,000 shares of its outstanding common stock for an aggregate cost of approximately $1.0 million, representing an average price of $29.44 per share.

Leasing Information

        Mack-Cali's consolidated in-service portfolio was 92.4 percent leased at March 31, 2003, compared to 92.3 percent leased at December 31, 2002.

        For the quarter ended March 31, 2003, the Company executed 155 leases totaling 1,018,926 square feet, consisting of 777,707 square feet of office space, 204,943 square feet of office/flex space and 36,276 square feet of industrial/warehouse space. Of these totals, 373,973 square feet were for new leases and 644,953 square feet were for lease renewals and other tenant retention transactions.

        During the quarter, the Company reduced its 2003 scheduled lease expirations by 353,903 square feet, from 8.3 percent (at December 31, 2002) to 6.8 percent (at March 31, 2003) of square footage, reducing 2003 expiring annualized rents by $6.5 million, from 7.6 percent (at December 31, 2002) to 6.3 percent (at March 31, 2003) of annualized rents.

        Highlights of the quarter's leasing transactions include:

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United States Life Insurance Company in the City of New York, a subsidiary of American International Group, Inc. (AIG), signed a 180,000 square-foot renewal for 10 years. US Life occupies the entire class A office building at 3600 Route 66 in the Jumping Brook Corporate Center in Neptune, New Jersey.



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Pharmaceutical firm Barr Laboratories, Inc. signed a new, 12-year lease for the entire 89,510 square-foot building located at 400 Chestnut Ridge Road in Woodcliff Lake, New Jersey.



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Toyota Motor Credit Corporation, the U.S. financing arm of Toyota Financial Services, a subsidiary of Toyota Motor, renewed leases totaling 22,396 square feet for an average of five years at 4 Gatehall Drive in Parsippany, New Jersey. The 248,480 square-foot, class A office property is 86.2 percent leased. In a separate transaction, Toyota Motor Credit Corporation renewed its lease for 7,656 square feet at 1000 Bridgeport Avenue in Shelton, Connecticut for five years. 1000 Bridgeport Avenue is a 133,000 square-foot, class A office building and is 70.2 percent leased.



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Kendle International, a global provider of clinical research and development services for the pharmaceutical and biotechnology industries, renewed its 21,243 square-foot lease for seven years at 6 Commerce Drive in Cranford, New Jersey. The 56,000 square-foot office building is 100 percent leased.



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E&B Giftware, LLC, a designer and manufacturer of a variety of consumer products for wholesale distribution, renewed its lease for 20,355 square feet and expanded by 8,075 square feet for an average of eight years at 4 Executive Plaza in the South Westchester Executive Park in Yonkers, New York. The 80,000 square-foot office/flex building is 99 percent leased.

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•

Sirenza Microdevices, a designer and supplier of radio-frequency components for communications equipment, signed a 10-year lease for two entire office buildings totaling 74,870 square feet located at 303 South Technology Court at Interlocken Technology Park in Broomfield, Colorado.



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Altria Corporate Services, Inc., a subsidiary of Altria Group, Inc., the parent company of Kraft Foods and Philip Morris, renewed its lease for 58,248 square feet and expanded by 13,036 square feet for 10 years at The Century Building, located on the North Loop in San Antonio, Texas. The 187,312 square-foot office property is 92.9 percent leased.

Information About FFO and CAD

        The Company considers FFO (after adjustment for straight-lining of rents and non-recurring charges) a relevant measure of REIT financial performance which the financial community desires REITs to provide. FFO is defined as net income (loss) before minority interest of unitholders (preferred and common) computed in accordance with generally accepted accounting principles ("GAAP"), extraordinary items, and sales of depreciable rental property, plus real estate-related depreciation and amortization. FFO should not be considered as an alternative for net income as an indication of the Company's performance or to cash flows as a measure of liquidity. FFO presented herein is not necessarily comparable to FFO presented by other real estate companies due to the fact that not all real estate companies use the same definition. However, the Company's FFO is comparable to the FFO of real estate companies that use the current definition of the National Association of Real Estate Investment Trusts ("NAREIT"), with the exception that it deviates as a result of adjustments made to the Company's FFO for straight-lining of rents and non-recurring charges. The Company adjusts its FFO calculation to remove the effects of straight-lining of rents because it believes that such adjustment more accurately reflects proper recognition of the Company's revenue that is contractually due for the respective periods presented. The Company also adjusts its FFO calculation for non-recurring charges, if any, because it believes that the inclusion of these costs, which are incurred specific to significant non-recurring events, can impact the comparative measurement of the Company's performance. A reconciliation of net income to FFO is included in the financial tables on page 25.

        The Company considers CAD another relevant measure of REIT financial performance which the financial community desires REITs to provide. CAD is defined as FFO (after adjustment for straight-lining of rents and non-recurring charges), reduced by non-revenue generating capital expenditures for building improvements, tenant improvements and lease commissions incurred during the period. CAD should not be considered as an alternative for net income as an indication of the Company's performance or to cash flows as a measure of liquidity. CAD presented herein is not necessarily comparable to CAD presented by other real estate companies due to the fact that not all real estate companies use the same definition. A reconciliation of net income to CAD is included in the financial tables on page 25.

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Key Financial Data

(a)

Includes preferred units on a converted basis into common units.

(b)

Calculated based on weighted average common shares outstanding, assuming redemption of operating partnership common units into common shares.

(c)

Calculated based on shares and units included in basic per share/unit computation, plus dilutive Common Stock Equivalents (i.e. convertible preferred units, options and warrants).

(d)

Includes preferred units on a converted basis into common units and minority interests in partially-owned properties.

(e)

Funds from Operations ("FFO") is calculated in accordance with the National Association of Real Estate Investment Trusts (NAREIT) definition, as published in October 1999, after adjustment for straight-lining of rents and non-recurring charges.

(f)

Cash Available for Distribution ("CAD") is defined as funds from operations, after adjustment for straight-lining of rents and non-recurring charges, minus non-incremental revenue generating tenant improvements, non-incremental revenue generating leasing commissions and recurring building improvements.

(g)

Reflects square feet leased at the Company's consolidated in-service portfolio, excluding in-service development properties in lease-up.

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Same Store Results and Analysis
(dollars in thousands)

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Unconsolidated Joint Ventures Summary

Breakdown of Unconsolidated Joint Ventures

(a)

The joint venture also has a parking lot operation on adjacent land.

(b)

This property was sold by the joint venture on April 1, 2003 for approximately $52.5 million.

(c)

Property consists of a three-story theater and retail complex.

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Unconsolidated Joint Venture Financial Information

        The following is a summary of the financial position of the unconsolidated joint ventures in which the Company had investment interests as of March 31, 2003 and December 31, 2002:

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        The following is a summary of the results of operations of the unconsolidated joint ventures for the period in which the Company had investment interests during the three months ended March 31, 2003 and 2002:

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Select Financial Ratios

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Debt Analysis
(as of March 31, 2003)

Debt Breakdown
(dollars in thousands)

Future Repayments
(dollars in thousands)

(a)

Actual weighted average LIBOR contract rates relating to the Company's outstanding debt as of March 31, 2003 of 1.36 percent was used in calculating revolving credit facility and other variable rate debt interest rates.

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Debt Maturities
(dollars in thousands)