Thirty-seven patients with Hirschsprung's disease (HD) underwent endorectal pull-through (ERPT). Six children had signs and symptoms similar to those of their preoperative state, and their conditions did not respond to conservative therapy. Anorectal manometry showed high anal canal pressure in these patients. Anorectal myectomy (ARM), which included posterior rectal myectomy with partial internal sphincterotomy, was performed 6 to 55 months after ERPT. Five patients had marked improvement, and one had a partial response. Anal canal pressure was reduced significantly in all six patients. ARM is recommended after ERPT if constipation, abdominal distension, or repeated enterocolitis, unresponsive to conservative therapy, occurs. ARM should be performed before the patient is considered a candidate for a secondary pull-through operation.