&NA;Uncertainty persists concerning the long‐term results of ileal pouch‐anal anastomosis performed for indeterminate colitis.PURPOSE:This study was designed to compare functional outcomes of ileal pouch‐anal anastomosis in patients with typical chronic ulcerative colitis and indeterminate colitis.METHOD:Seventy‐one ileoanal pouch patients were identified with a diagnosis of indeterminate colitis. Mean follow‐up was 56 months. Outcomes were compared with 1,232 chronic ulcerative colitis patients after ileal pouchanal anastomosis. Mean follow‐up was 60 months.RESULTS:(mean±SD) There was no difference in the frequency of daily bowel movements (indeterminate colitis, 7±3,vs.chronic ulcerative colitis, 7±2). Daytime and nighttime incontinence rates were likewise similar. Prevalence of pouchitis was identical (33 percent). However, failure rate was higher in the indeterminate colitis group (indeterminate colitis, 19 percent,vs.chronic ulcerative colitis, 8 percent; (P=0.03)).CONCLUSIONS:At a mean of nearly five years after surgery, failure appears to occur more frequently in patients with indeterminate colitis than in patients with chronic ulcerative colitis. However, the great majority of indeterminate colitis patients (>80 percent) have long‐term functional results identical to those of patients with chronic ulcerative colitis.