Toxic enterocolitis can occur in patients with Hirschsprung disease. Rarely, it has been reported to occur in patients treated for Hirschsprung disease by a pull-through procedure. This is generally reported to be a severe and life-threatening event. We report three patients with successful pull-through procedures who developed a very mild, but clinically significant colitis at 4 mo, 3 yr & 7 yr following their repair. All the patients had diarrhea as their only symptom. None had bleeding or abdominal pain. No infectious agents were found. On flexible sigmoidoscopy, the mucosa appeared normal in all patients. However, the biopsies revealed a mild increase in cellularity of the lamina propria, with increased lymphocytes, plasma cells and occasional neutrophils and eosinophils, associated with occasional cryptitis. There were no crypt abscesses nor granulomas noted. While the amount of diarrhea seemed out of proportion to the very mild degree of inflammation recognized microscopically, all three patients responded to treatment with Asulfadine. Whether the etiology of the mild inflammation found in these patients is the same as in patients with toxic enterocolitis is unknown. However, unexplained diarrhea in post pull-through patients should be evaluated with mucosal biopsies . If inflammation is present, the patients should be treated with anti-inflammatory medications.