Renal arteriography remains the only study to identify and define correctly both location and extent of renal artery stenosis. Because other studies do not adequately identify all children who have renal artery disease, it is reasonable to perform renal arteriography in those children with severe hypertension who do not have another readily identifiable cause for their hypertension. On the other hand, in children with less profound elevation of blood pressure in whom there is no other definable cause, it is possible to defer renal angiography. In these children with mild or moderate hypertension, studies such as the captopril 99mTc-DTPA scan or intravenous digital subtraction angiography may identify those for whom arteriography is more likely to have abnormal results.