A study group was formed to undertake furtherinvestigation of the problems involved in the classification of anorectal anomalies. At first, a registration form including standardized techniques for clinical and roentogenologic investigation was defined, and then 254 cases were collected and analyzed by referring these materials to the international Classification by the Melbourne group in 1970. Our analysis disclosed: (1) It is imperative to establish a registration form with footnotes describing standardized techniques for clinical and roentogenologic investigations; (2) The rectourethral fistula has been classified simply as high type under the present International Classification, but differences in the levels of the rectal pouch and of the point of fistula, as observed in the collected materials, tends to show that further subdivision of this anomaly may be indicated; (3) An abnormal skin fold at the anal and/or perineal sites is not always diagnostic of low type, specifically of covered anus-complete. Conversely, some infants with high type anomaly had abnormal skin folds; and (4) Two types of anomaly, which have not been well described in the present classification, were detected. They were “rectal membraneous atresia” and “recto-penile fistula”.