The identification of renal abnormalities in the human fetus has focused attention on considerations for intervening to correct defects in utero as an alternative to abortion. The fervor which has characterized unproven, though seemingly logical measures attempted unsuccessfully thus far to prevent continued renal injury and pulmonary hypoplasia in the fetus with obstructive uropathy, affords an opportunity to discuss ethical issues which will encumber further experimental approaches for treating the defective human fetus. Such uncharted measures must be scrutinized rigorously not only for valid scientific principles, but also for consideration given to ethical concerns.