Exhibit 99.1


                    CERTIFICATION PURSUANT TO
                         18 U.S.C. 1350,
                     AS ADOPTED PURSUANT TO
          SECTION 906 OF THE SARBANES-OXLEY ACT OF 2002


In  connection with the Quarterly Report of AEI Income  &  Growth
Fund  XXI Limited Partnership (the "Partnership") on Form  10-KSB
for  the  period  ended December 31, 2002,  as  filed  with  the
Securities  and  Exchange  Commission on  the  date  hereof  (the
"Report"), I, Robert P. Johnson, President of AEI Fund Management
XXI,  Inc.,  the  Managing General Partner  of  the  Partnership,
certify,  pursuant  to  18 U.S.C. 1350, as  adopted  pursuant  to
Section 906 of the Sarbanes-Oxley Act of 2002, that:

     1.   The  Report  fully  complies with the  requirements  of
          Section  13(a) or 15(d) 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 Partnership.


                           /s/ Robert P Johnson
                               Robert P. Johnson, President
                               AEI Fund Management XXI, Inc.
                               Managing General Partner
                               March 25, 2003