BACKGROUND/PURPOSE The anticipated level of aganglionosis can influence the surgical approach to Hirschsprung's disease. The aim of this study was to determine the accuracy of the contrast enema in predicting this level. METHODS Over a 6-year period (1995 through 2000), 88 patients with Hirschsprung's disease underwent surgical correction. Preoperative contrast enema findings were available for 75 of these patients and were compared with operative and pathology reports. Data were analyzed by chi(2). RESULTS The contrast enema showed a transition zone suggestive of Hirschsprung's disease in 67 of 75 patients (89%). In 59 of 67 (88%), the pathologic and radiographic transition zones were concordant. Seven of the 8 patients with discordant studies had total colonic (n = 5) or long-segment (n = 2) disease. Contrast enema correctly predicted the level of aganglionosis in 55 of 62 (89%) patients with rectosigmoid disease but only 4 of 13 (31%) of those with long-segment or total colonic disease (P <.01). Of the patients with a radiographic transition zone in the rectosigmoid, 54 of 60 (90%) had a matching level of aganglionosis. CONCLUSIONS In rectosigmoid Hirschsprung's disease, the location of the radiographic transition zone correlates accurately with the level of aganglionosis in 90% of cases. However, the small incidence of discordance between anticipated level of aganglionosis and operative findings should be recognized, particularly when planning a one-stage transanal pull-through.