The findings on the plain abdominal radiographs of 15 patients with cytomegalovirus (CMV) colitis and AIDS were reviewed and compared to an age, sex, CD4 count and symptom-matched control group. The radiographs were examined for mucosal thickening, bowel dilatation, pneumatosis and perforation. Nodular mucosal lesions were the most significant abnormality in those with CMV colitis being present in seven compared to none in the control group (P = 0.006 two tailed). Differences between the CMV colitis group and the control group as regards the other features were not significant. The finding of pneumatosis is the first time this has been described in patients with CMV colitis and AIDS. No evidence of perforation was demonstrated and this is attributed to a high index of suspicion in those with characteristic signs and symptoms in addition to early sigmoidoscopy and prompt treatment.