&NA;A case of adenocarcinoma complicating the outflow tract remnant of a previously excised ileoanal pouch is described. The pouch had failed because of unsuspected Crohn's disease. This is the first reported case of malignancy complicating a pouch that had been constructed in a patient with Crohn's disease. More importantly, it demonstrates that carcinoma may develop in the outflow tract remnant leftin situafter simple pouch excision. This case suggests that patients who require pouch excision may benefit from excision of the outflow tract.