Nineteen children with chronic ulcerative colitis refractory to medical therapy and one with multiple polyposis, all under 20 years of age, underwent total colectomy, mucosal proctectomy, and endorectal ileal pull-through with ileoanal anastomosis at the UCLA Medical Center during a 4 1/2-year period (mean age, 14.4 years). Seventeen patients underwent second-stage closure of the ileostomy with construction of a side-to-side isoperistaltic ileal reservoir (mean, 6 months) after the ileal pull-through operation. The anastomosis extended over a 20- to 30-cm distance and the lower end was placed within 6 to 8 cm of the ileoanal anastomosis. Transient reservoir inflammation, which occurred in more than half of the patients, was reduced by the use of oral Metranidazole and was rare 6 months postoperation. Cuff abscess in one patient did not respond to long-term antibiotics and required ileostomy as well as eventual takedown of the reservoir. Two patients developed obstruction of the ileum below the reservoir due to an extended distance between the reservoir and anal anastomosis, requiring transient ileostomy. Fourteen of the 17 children who have undergone lateral reservoir construction have achieved a good-to-excellent result, with complete continence and an average of five stools per 24 hours after 6 months. Seven of the 14 now participate in competitive athletics. Three children await construction of the reservoir.