Twenty-four AIDS patients, who underwent gastrointestinal evaluation, died from their disease and were autopsied. Seven had Cytomegalovirus colitis (group I) and 17 did not (group II). Clinical manifestations, digestive lesions, and infections were compared in the two groups. Chronic watery diarrhea was present in all the patients with colitis but was also present in 65% of the patients without colitis. Hematochezia was present only in the group with colitis (one of seven patients) but appeared late in the diarrheal course, due to necrotizing colitis. No other difference were noted between the two groups (mean duration of diarrhea, frequency and nature of the other infections). As for group I specifically, colonic ulcerations due to Cytomegalovirus were present in all the patients, varying from punctate and superficial erosions to deep ulcerations, with granular and friable intervening mucosa. Severe colonic lesions appeared during the course of Cytomegalovirus colitis in two patients who developed lethal necrotizing colitis. Finally, the clinical and pathologic features of these seven cases were compared to other reports of Cytomegalovirus infection of the colon.