The prognosis of ulcerative colitis has been studied in 122 patients with this disease who had been referred to Bolgna from various parts of Italy and were then followed up. The overall mortality rate was 4.9% and the percentage of patients who were treated by total colectomy was 15.5%. Postoperative mortality was 10.5%, and the percentage of patients who developed carcinoma of the colon was 0.8%. All these figures fall within the range of values for the relevant variables quoted by previous authors from different countries. It is concluded that the prognosis of ulcerative colitis in the 122 Italian patients in the present study was similar to that reported previously in patients of other nationalities.