Three cases of congenital renal hypoplasia, 2 children and 1 adult, are reported. The characteristic findings of renal hypoplasia on angiography are a proportionally smaller renal artery and arterial branches. Angiography would give a definite diagnosis when one doubts whether this condition is congenital or due to secondary atrophy. A significant cure of the renovascular hypertension was noted following nephrectomy of the hypoplastic kidney.