In utero diagnosis of severe oligohydramnios and fetal ureteral pelvic outlet obstruction resulted in the placement of nephrostomy catheters in two fetuses. The amniotic fluid index improved, mid-chest thoracic circumference increased and renal calyceal dilation decreased in both patients. Both neonates had evidence of pulmonary hypoplasia but survived. This new technique offers an alternative for antenatal management of obstructive uropathy when the bladder is not accessible or is distal to the site of the obstruction.