Purpose: The aim of this study was to present the technique of megasigmoid resection and anal reconstruction by complete posterior sagittal approach for the children with severe constipation and fecal incontinence after anoplasty. Methods: Six patients (age, 2 to 18 years) born with imperforate anus and originally treated with perineal anoplasty suffered from intractable constipation and fecal incontinence. Contrast enema showed massive dilated and aperistaltic rectosigmoid colon with fecal impaction. Resection of the dilated bowel and anal reconstruction were completely performed by posterior sagittal approach. Results:The mean operating time was 205 minutes (range, 125 to 265 minutes) and the average length of resected colon was 23.3 cm (range, 10 to 40 cm). There were no intraoperative or postoperative complications. By 2 to 4 months after the operation, all patients obtained voluntary bowel movement. On follow-up at 6 to 24 months postoperative, no patient had constipation or required use of the laxatives again. Four of 6 patients suffered from grade 1 soiling, and the other 2 had grade greater than 1 soiling. None had urinary retention or incontinence after the procedure. Conclusion: Resection of dilated rectosigmoid colon and anal reconstruction for the patients with severe constipation and fecal incontinence after anoplasty can be performed successfully using a posterior sagittal approach. Copyright (C) 2000 by W.B. Saunders Company.