The course of ulcerative colitis is illustrated by the sequence of events occurring in 134 children with the disease followed 2 to 26 years. The well-known erratic but persistent nature of the disease is further documented. Carcinoma of the colon developed in 6 patients (4.4 per cent), all of whom had had the disease more than 10 years, cirrhosis of the liver complicated 2 cases but the majority of deaths (19 of 26 in the series) were attributed to the disease itself. Proper respect is paid to the contribution of all forms of therapy, including psychiatry, but the threat of carcinoma of the colon even after years of well-being is so great that the authors urge combined iliostomy and colectomy for all severe or persistent cases.