EXHIBIT 99.1
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         Certification of Chief Executive Officer Pursuant to
                        18 U.S.C. Section 1350,
                        As Adopted Pursuant to
             Section 906 of the Sarbanes-Oxley Act of 2002



In connection with the Quarterly Report of Jones Lang LaSalle Incorporated
(the "Company") on Form 10-Q for the period ending March 31, 2003 as filed
with the Securities and Exchange Commission on the date hereof (the
"Report"), Christopher A. Peacock, as Chief Executive Officer of the
Company, hereby certifies, pursuant to 18 U.S.C. Section 1350, as adopted
pursuant to Section 906 of the Sarbanes-Oxley Act of 2002, to the best of
his knowledge, that:

     (1)   The Report fully complies with the requirements of section
           13(a) of the Securities Exchange Act of 1934; and

     (2)   The information contained in the Report fairly presents, in
           all material respects, the financial condition and results of
           operations of the Company.







/s/ Christopher A. Peacock
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Christopher A. Peacock
Chief Executive Officer
May 6, 2003




This certification accompanies the Report pursuant to Section 906 of the
Sarbanes-Oxley Act of 2002 and shall not, except to the extent required by
the Sarbanes-Oxley Act of 2002, be deemed filed by the Company for purposes
of Section 18 of the Securities Exchange Act of 1934, as amended.