Renal artery stenosis (RAS) is one of the most common causes of severe arterial hypertension in infants. Its management is very difficult, especially when present in a single kidney. We report a case of severe hypertension caused by RAS of congenital single pelvic kidney in a 4-month-old boy. The patient presented with cardiorespiratory insufficiency that was first treated as acute fulminate myocarditis. Medical treatment of arterial hypertension was disappointing, as it had to be balanced between congestive cardiac failure and acute renal failure. Percutaneous transluminal angioplasty (PTA) done by coronary balloon dilatation catheters through the left axillary access was successful. Following dilatation of the renal artery, blood pressure decreased and its good control was possible by only one drug. With improved medical blood pressure control and normal growth development, the reassessment of clinical therapy options adjusted to a larger vessel size would be possible. Renovascular hypertension due to RAS in infants with a solitary kidney is difficult to control by medical treatment alone. PTA should be considered as a viable option in infants with refractory hypertension due to renal artery stenosis in a solitary kidney, since it has the potential of improving hypertension while preserving renal function.