Twenty-seven patients with severe acute amebic dysentery were studied at the International Centre for Diarrhoeal Disease Research Hospital in Dacca, Bangladesh. Patients were divided into two groups according to their pretreatment proctoscopic mucosal pattern. Those with mild lobular patterns (five patients) had milder illness; posttreatment air-contrast barium enema examinations were normal except for subtle mucosal abnormalities in two (40%). In contrast, patients with necrotic ulceration proctoscopic patterns (22 patients) had a more severe illness; 19 (86%) has ulcerations, haustral abnormalities, and/or strictures demonstrated on posttreatment barium enema examinations. Persistent strictures were found in eight of 10 patients with necrotic ulceration patterns who had sequential barium enema examinations up to 9 months after treatment. These observations indicate that despite successful therapy with metronidazole, there is a high incidence of persisting colonic abnormalities in patients with the necrotic ulceration pattern. Since proctoscopy has a useful predictive value, it should be performed in all patients with severe amebic dysentery.