Antihypertensive agents differ as to the degree of hypotension which results from their use. In an attempt to evaluate various agents, a double-blind study was begun in January, 1956. Seventy-four patients received placebo and ergotoxine alkaloids parenterally. Sixty received placebo and drugs orally. For 59 weeks, parenteral placebo administration caused a significant decrease in systolic pressure. Parenteral drug and placebo administration was followed by a significant decrease in diastolic pressure through the 143rd week. Patients receiving placebo orally experienced no significant change in pressure. Decreases in systolic and diastolic pressure followed oral administration of the ergotoxine alkaloids, reserpine, and a combination of rauwolfia, protoveratrine, and phenoxybenzamine hydrochloride. Dihydroergocornine orally did not decrease the blood pressure.