In order to evaluate the efficiency of antenatal diagnosis and postnatal management of urinary malformations, we reviewed 142 cases from October 1988 to December 1992 with abnormalities detected by routine ultrasound. A routine karyotype analysis showed 7 fetuses with chromosomal defects. Nine cases with isolated bilateral urinary tract dilatation underwent pelvic fetal urine sampling in order to assess antenatal renal function. The 142 cases comprised 107 children born alive (group I) and 35 intrauterine fetal deaths (group II). In group I, 79 kidneys had a transient pyelectasis, and 11 kidneys had a hydronephrosis which disappeared at postnatal examination. Among 103 pyelectasis cases detected during the second trimester of pregnancy, 22 kidneys were pathological after birth (positive predictive value (PPV) = 21.4%) with 17 ureteropelvic junction obstructions. The PPV was 66% when ultrasound showed hydronephrosis at the end of pregnancy. In that group, 15 cases had vesicoureteric reflux, with 5 cases where the homolateral upper urinary tract was morphologically normal in utero. Group II comprised 27 fetuses with multiple defects in other systems, and 8 cases with urological defects only 7 of which had urethral anomalies. This study confirmed the benefit of antenatal diagnosis for uropathies, and the advantage of prenatal consultation between pediatric surgeon and parents in order to explain what anomalies are involved and to program postnatal follow-up.