During the period from 1972 to 1992, 59 children received surgical treatment at the University of Louvain Medical School for biopsy-proven Hirschsprung's disease (HD). The extent of aganglionosis was as follows: short segment restricted to the rectosigmoid or descending colon (n = 44, 75%); long segment (n = 9,15%); ultra-short segment (n = 3, 5%); unknown length because of death without autopsy (n = 3, 5%). The median age at operation was 7 months for short-segment disease compared with 14 months for those with long-segment disease. Surgical procedures used for short-segment disease were Swenson with colostomy (n = 16), Swenson-Pellerin without colostomy (n = 27), Duhamel (n = 1), and for long-segment disease were Martin (n = 3), Swenson-Deloyers (n = 2), Swenson-Boley (n = 2) and ileostomy only in = 2). Lynn's sphincteromyotomy was performed in the three ultra-short cases. There were six deaths (10%) at a median age of 86 days (range, 28 to 1545 days), three had long-segment disease, and the others were not classified because of death before curative surgery. Enterocolitis (EC) was the most common cause of death (five cases) and was also the major source of morbidity after curative surgery (12 of 44, 27%) in short-segment patients, three of seven (43%) in long-segment patients. The functional success of the procedure was evaluated in 70% of the surviving patients (37 of 53; mean follow-up, 8.7 years; range, 1.2 to 21.5), using a novel semiquantitative scoring system, specifically designed for children who have HD. This system assesses normal stool evacuation, abdominal distention, soiling, and severe incontinence. The results were compared with those from a population of 39 healthy children and adolescents and demonstrated progressive improvement in function during childhood and adolescence (P = .04) for patients treated for short-segment disease. However, function was found to be consistently poorer in all age groups when compared with healthy controls (5 to 10 years, P < .01; 10 to 15 years, P < .05; > 15 years, P < .01).