Renal hypoplasia is defined as a subnormal growth of the kidney with a distinct cortex and medulla and is recognizable as a kidney. It is known that renal hypoplasia can induce hypertension by reduction of functioning nephron. Patients with reduced functioning renal mass by surgical or medical causes have a risk to develop hypertension. Patients with congenital reduction of functioning nephron have more frequently showed renal insufficiency. But renal hypoplasia induced hypertension is very rare and reported rarely in international literature. We report two cases of hypertension associated with congenital renal hypoplasia.