One hudred and fiftyfive patients with anorectal malformation have been surgically treated from 1962 to 1980 at our institute. Postoperative anorectal functions were evuluated in 116 cases (more than 1 year postoperatively and older than 2 years of age) by Kelly's clinical score. In several cases, radiological examination and anorectal manometric studies were also performed. Low type: Surgical procedure was done by perineal approach. 64 of 73 cases (89%) showed "good" results. Postoperative anal musosal prolapse or stenosis required anoplasty in 12 cases (16%). Intermediate type: 8 cases were operated on by abdominoperineal approach, and 7 cases by perineal approach. 10 of 15 cases (68%) showed "good" results. As to results, no signficance was observed between these two different surgical approaches. The only case showing "poor" result was associated with Down's syndrome. High type: 28 cases were surgically treated by abdomino-perineal approach, and 39% of them had "poor" results. Pickerell's or Kottmeier's procedures were performed for incontinence in 7 cases, and anoplasty for anal mucosal prolaps in 21 cases. Sixteen cases with high and intermediate anomaly were evaluated twice by the same method 5 years ago and currently. Nine 9 of 16 cases showed improvement. In 4 of these 9 cases there was an improvement in clinical score by Kottmeier's operation or anoplasty, whereas the improvement was obtained without any surgical treatment in 5. Twenty-eight patients were studied by radiological examination and anorectal anorectal manometries. In "good" or "fair" cases, the pressure gradient between the rectum and the anal canal was more than 11 cmH_2O, and the anal resting pressure was more than 18 cmH_2O. In these cases, the PC-R angle (angle of the rectal floor line against the P-C line on lateral X-ray view) ranged from -10° to +20°, and the rectal dilation ratio (the rectal transverse diameter divided by the pelvic transverse diameter on frontal X-ray view) ranged from 40% to 60%. The cause of "poor" result with incontinence or severe constipation could be differentiated by evaluation of the rectal dilatation ratio and the anal resting pressure.
