Renal hypertension is divided into two categories: renoprival (excretory failure) and renovascular. The diagnostic and therapeutic implications of this classification are presented. Two cases of unilateral renal disease are discussed, emphasizing radiologic diagnosis and pharmacologic testing with tetraethyl ammonium chloride. Indications and expectations for nephrectomy are presented. Antihypertensive drugs are reviewed, their relative usefulness and probable mechanism of action are suggested. Two opportunities for preventing renal hypertension are offered: chronic pyelonephritis and radiation nephritis.