Unilateral renal artery stenosis can lead to a non-functional kidney which secretes large amounts of renin. Four cases are presented in which the high renin state resulted in hypertension, proteinuria from the intact contralateral kidney, and secondary aldosteronism. The proteinuria was in the nephrotic range, which is unusual in renovascular hypertension, but gradually disappeared after correction of the high renin state by removal of the renin-secreting kidney or administration of an ACE inhibitor. Accordingly, when there is marked proteinuria in the presence of new-onset or rapidly progressive hypertension, hypokalaemic alkalosis, and a high peripheral PRA, renal artery stenosis should be considered since the proteinuria may be reversible after nephrectomy, repair of the ischaemic kidney or medical therapy.