SUMMARY A study of the comparative hypotensive effects and side effects of reserpine, alseroxylon, deserpidine and rescinnamine revealed that:
1 Reserpine at an average dosage of 0.5 mg. and the alseroxylon fraction at an average dosage of 4.5 mg. both produced a satisfactory hypotensive response and the incidence of side effects of these agents when given during the day was similar quantitatively and qualitatively. 2 Deserpidine produced a hypotensive response which was similar to that of reserpine at the dosage employed and the incidence of side effects was less than that of reserpine (when the drug was given during the day) in that lethargy and depression were less common. When deserpidine was given at night nervousness and insomnia were produced. 3 Rescinnamine in an average dose of 1.5 mg. had the least hypotensive effect of any of the drugs tested.