Twelve patients with acute dissecting aneurysms have been treated with antihypertensive medications. These patients all presented with chest or back pain and had systolic blood pressures of greater than 160 mm Hg. They responded to drug-induced hypotension with loss of pain and stabilization of their general condition. Two patients died during the initial phase of therapy. In both these cases there was inadequate control of the blood pressure on an altered medication regime. Ten patients have now been followed for periods ranging from 1 month to 1 year. There has been no evidence either symptomatically or roentgenographically that these patients have had progression of their disease process.