Gallium-67-citrate scanning was performed in 9 patients with ulcerative colitis. In all patients there was good correlation between the regional uptake of gallium and the extent and activity of disease. In 2 patients the scans were positive during an acute exacerbation and reverted to normal or near normal during clinical remission. In one patient in whom the colon was resected because of toxic dilatation, good correlation was found between pathologic and scintigraphic examinations. During the acute attack of ulcerative colitis, when colonoscopy or barium enema may be contraindicated, gallium scanning may be a noninvasive means of assessing the extent of colonic involvement. It may also be an alternative means of following the clinical course of the disease.