Nifenalol is the beta-receptor antagonist. It has optical isomers. The racemic mixture and the levo-isomer are active in antagonizing beta-receptors, but the dextro-isomer is inactive. The levo-isomer seems to be about twice as active in blocking beta-receptors as the racemate. Nifenalol is virtually devoid of local anesthetic properties in contrast to procaine, propranolol, and butidrine. Nifenalol exacerbated the fighting behavior in male mice by foot-shock. Nifenalol has been studied in patients with coronary artery disease. It afforded the coronary patient good protection against angina and ischemic changes in the EKG. It was further noted that nifenalol had no antiarrhythmic action and that it was devoid of evident side effects. Nifenalol possessed weak action against tremorine and oxotremorine induced tremor.