TWELFTH AMENDMENT TO PURCHASE AGREEMENT

     This Twelfth Amendment to Purchase Agreement (the "Twelfth
Amendment") dated the ___ of December, 2005, by and between AEI
REAL ESTATE FUND XVIII LIMITED PARTNERSHIP, a Minnesota limited
partnership  of  1300  Wells Fargo Place, St.  Paul,  Minnesota
("Seller")  and  TEXAS  TACO  CABANA,  L.P.,  a  Texas  limited
partnership of 8918 Tesoro Drive, Suite 200, San Antonio, Texas
78217 ("Buyer").

                           RECITALS

      WHEREAS  Seller and Buyer entered into a certain Purchase
Agreement  dated  May 21, 2003 covering real property  commonly
known  as  7339  San Pedro Avenue, San Antonio, Texas  as  more
particularly described therein (the "Purchase Agreement"); and

      WHEREAS  by  First Amendment to Purchase Agreement  dated
July  18, 2003, the Seller and Buyer extended the Due Diligence
Period thirty (30) days to expire August 20, 2003; and

      WHEREAS  by Second Amendment to Purchase Agreement  dated
August  12,  2003,  the  Buyer  and  Seller  extended  the  Due
Diligence  Period  sixty (60) days beyond August  20,  2003  to
October 20, 2003; and

      WHEREAS  by  Third Amendment to Purchase Agreement  dated
October  16,  2003,  the  Seller and  Buyer  extended  the  Due
Diligence Period beyond October 20, 2003 to February 17,  2004;
and

      WHEREAS  by Fourth Amendment to Purchase Agreement  dated
February  17,  2004, the Seller and Buyer, among  other  things
extended  the  Due  Diligence Period  to  April  16,  2004  and
provided  for  two  (2) additional, thirty (30)  day  extension
periods beyond April 16, 2004; and

        WHEREAS by Fifth Amendment to Purchase Agreement  dated
June  10,  2004,  the  Seller and Buyer,  among  other  things,
extended  the  Due Diligence Period to September 16,  2004  and
provided  for  two  (2) additional, thirty (30)  day  extension
periods beyond September 16, 2004; and

      WHEREAS  by  Sixth Amendment to Purchase Agreement  dated
November  9,  2004, the Seller and Buyer, among  other  things,
extended  the  Due  Diligence Period to January  17,  2005  and
provided  for  three (3) additional, thirty (30) day  extension
period beyond January 17, 2005; and

      WHEREAS by Seventh Amendment to Purchase Agreement  dated
January  13,  2005, the Seller and Buyer, among  other  things,
extended the Due Diligence Period to March 17, 2005; and

      WHEREAS  by Eighth Amendment to Purchase Agreement  dated
March  4,  2005,  the  Seller and Buyer,  among  other  things,
extended  the Due Diligence Period to May 16, 2005 and provided
for two (2) additional thirty (30) day extension periods beyond
May 16, 2005; and

      WHEREAS  by  Ninth Amendment to Purchase Agreement  dated
July  14,  2005,  the  Seller and Buyer,  among  other  things,
extended the Due Diligence Period to September 15, 2005; and

      WHEREAS  by  Tenth Amendment to Purchase Agreement  dated
September  8,  2005, the Seller and Buyer, among other  things,
extended the Due Diligence Period to October 15, 2005; and

      WHEREAS by Eleventh Amendment to Purchase Agreement dated
October  13,  2005, the Seller and Buyer, among  other  things,
extended the Due Diligence Period to December 15, 2005; and
     WHEREAS  Buyer  and  Seller desire to amend  the  Purchase
Agreement to extend the Due Diligence Period as more fully  set
forth hereinafter.

     NOW, THEREFORE, for and in consideration of the sum of ten
and  00/100  Dollars ($10.00) the terms, conditions and  mutual
covenants and agreements contained herein, and other  good  and
valuable consideration the receipt and sufficiency of which  is
hereby acknowledged, Seller and Buyer agree to amend the  terms
of the Purchase Agreement as follows:

     1.   The  introduction  and Whereas paragraphs  above  are
          incorporated into this section by reference as if more
          fully set forth herein.

     2.   All capitalized terms used herein shall have the same
          meaning as ascribed to them in the Purchase Agreement
          unless a contrary meaning is specifically set forth
          herein.

     3.   Section 6 of the Purchase Agreement is hereby amended to
          extend the Due Diligence Period so that the Due Diligence
          Period shall now expire on March 31, 2006.

     4.   All  other dates in the Purchase Agreement  that  are
          dependent upon the Due Diligence Period shall be calculated
          based on the expiration date for the Due Diligence Period of
          March 31, 2006.

     5.   Except as modified herein, all other terms, conditions,
          and covenants in the Purchase Agreement remain in full force
          and effect.

     IN  WITNESS WHEREOF, the parties have hereunto signed this
     Twelfth Amendment.

                              TEXAS TACO CABANA, L.P.

                              By:  T.C.  Management,  Inc.,   A
                                   Delaware   corporation,   it
                                   general partner

                              By:   /s/ William E Myers
                              Name:     William E. Myers
                              Title:    Vice President


                              AEI   REAL   ESTATE  FUND   XVIII
                              LIMITED PARTNERSHIP

                              By:  AEI  Fund Management  XVIII,
                                   Inc.,       a      Minnesota
                                   corporation,  it   corporate
                                   general partner

                              By:   /s/ Patrick Keene
                              Name:     Patrick Keene
                              Title:    Chief Financial Officer