<ARTICLE> 5 <CIK> 0000931755 <NAME> AEI INCOME & GROWTH FUND XXI LIMITED PARTNERSHIP <PERIOD-TYPE> 9-MOS <FISCAL-YEAR-END> DEC-31-1998 <PERIOD-END> SEP-30-1998 <CASH> 852,942 <SECURITIES> 0 <RECEIVABLES> 3,334 <ALLOWANCES> 0 <INVENTORY> 0 <CURRENT-ASSETS> 856,276 <PP&E> 18,375,376 <DEPRECIATION> (692,517) <TOTAL-ASSETS> 18,539,135 <CURRENT-LIABILITIES> 528,582 <BONDS> 0 <PREFERRED-MANDATORY> 0 <PREFERRED> 0 <COMMON> 0 <OTHER-SE> 18,010,553 <TOTAL-LIABILITY-AND-EQUITY> 18,539,135 <SALES> 0 <TOTAL-REVENUES> 1,388,083 <CGS> 0 <TOTAL-COSTS> 606,311 <OTHER-EXPENSES> 0 <LOSS-PROVISION> 0 <INTEREST-EXPENSE> 0 <INCOME-PRETAX> 1,017,149 <INCOME-TAX> 0 <INCOME-CONTINUING> 1,017,149 <DISCONTINUED> 0 <EXTRAORDINARY> 0 <CHANGES> 0 <NET-INCOME> 1,017,149 <EPS-PRIMARY> 42.26 <EPS-DILUTED> 42.26