Exhibit 32
                    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-QSB
for the period ended March 31, 2006, as filed with the Securities
and  Exchange  Commission on the date hereof (the "Report"),  the
undersigned, Robert P. Johnson, President of AEI Fund  Management
XXI,  Inc., the Managing General Partner of the Partnership,  and
Patrick  W. Keene, Chief Financial Officer of AEI Fund Management
XXI,  Inc., each 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
                              May 5, 2006


                          /s/ Patrick W Keene
                              Patrick W. Keene, Chief Financial Officer
                              AEI Fund Management XXI, Inc.
                              Managing General Partner
                              May 5, 2006