Although Hirschsprung's disease (HD) typically presents in the newborn period, it is often diagnosed in older children, in whom the presentation and management remain poorly defined. We hypothesized that older patients with HD have a milder variant of the disease with an improved prognosis compared with those diagnosed earlier. Children with HD (1995-2001) were divided into Group I (diagnosis before 30 days) and Group II (after 30 days). Patients with total colonic disease were excluded. There were 66 patients; 47 in Group I and 19 in group II. Mean age at diagnosis was 7.1+/-1.3 days (range 1-30 days) versus 27+/-10 months (1.3 months-19 years). Older children differed mainly in the symptoms at presentation and the length of the involved segment of aganglionosis. Surgical strategies were applied equally in both groups. Complications, including postoperative enterocolitis, occurred equally, but the length of stay and costs were lower in Group II. The delayed diagnosis of HD does not worsen outcomes of older children with HD. This finding implies that these children have a milder form of the disease, perhaps because of adaptation to the aganglionic state.