A decade has passed since Martin and associates presented the first series of endorectal ileal pull-through (PT) procedures with straight ileoanal anastomosis for treatment of ulcerative colitis and polyposis. During the ensuing years, several medical centers have reported their results using the PT. Although some children have experienced good results, the majority of adults and children have had severe problems associated with high stool frequency, urgency, and incontinence. Between 1977 and 1987, 12 patients underwent colectomy and straight PT for ulcerative colitis or familial polyposis under the direction of a single surgeon. In this group, the average number of stools varied from six to 45 movements per 24 hours (mean, 18). In seven patients, high stool frequency (mean, 24 per 24 hours), partial fecal incontinence, and urgency that led to moderate to severe limitation in physical, social, work, and sexual activities made it necessary to convert the straight PT to an ileal reservoir. For each of these patients, the ileal PT segment was separated from the rectal muscle cuff, a lateral isoperistaltic reservoir was constructed, and the ileoanal anastomosis was re-established in a one-stage operation. One additional patient decided to return to a conventional ileostomy. All seven patients who underwent conversion to a PT with reservoir had no major complications, and each improved markedly in their clinical status. Daytime stool frequency was reduced by a mean of approximately 50%, whereas nocturnal frequency was decreased by a mean of 60%. Incontinence and fecal urgency were relieved significantly. In conclusion, for patients who develop problems with a straight PT procedure and who desire to avoid a permanent ileostomy, conversion to a PT with a lateral ileal reservoir is a valuable alternative with low risk and a high likelihood of success.