An essential prerequisite for the correct surgical approach of the congenital anorectal anomalies is a precise diagnostic work-up demonstrating the level of the atresia and the nature of possibly associated anomalies. To be acquainted with basic embryology allows a better understanding of this pathology. In this study the value of clinical and radiological parameters has been analysed in sixty cases. An accurate diagnosis was established in one half of the patients only by clinical examination. In the other half, the X-ray with the child inverted according to Wangensteen and Rice proved to be frequently unreliable in contrast with opacification technics. In boys, retrograde urethrography (personal modification) demonstrated the fistula and its location in two-thirds of the cases with a doubtful clinical examination; similarly vaginal and rectal opacification led to a correct diagnosis in one half of the girls. During these investigations with a contrast medium, attention should be focused on the puborectalis sling in contraction and relaxation and its relationship with the terminal part of the bowel. In the remaining cases a colostomy or dilatation of the fistula during the neonatal period allowed the deferral of the definitive diagnosis.