In open and double-blind trials, tiapamil was given intravenously and/or orally to 22 patients with coronary heart disease and exertional angina. Multistage bicycle exercise tests were performed before and after drug treatment and patients acted as their own controls. Thallium-201 exercise myocardial imaging was also performed. Exercise tolerance increased and angina was improved under tiapamil treatment. Heart rate and blood pressure decreased slightly, consistent with reduced myocardial oxygen demand. Myocardial oxygen consumption, as indicated by the pressure-rate product, varied little, but exercise myocardial imaging indicated an increase in regional perfusion. The findings suggest that tiapamil is an effective antianginal agent.