A retrospective review of 123 cases of imperforate anus demonstrated a 41.5% incidence of associated genitourinary anomalies. The frequency and severity of associated GU anomalies was directly related to the level of the fistula between the blind-ending rectum and the GU tract. High-level fistulae to the bladder in males and the cloaca in females demonstrated a 64.7% incidence of associated GU anomalies. In contrast, lower level fistulae to the perineum showed a 30.3% incidence of GU anomalies. Classification of anorectal anomalies by fistula level provides no accurate mean of predicting the likehood of an associated GU malformation.