The efficacy of verapamil in a dose of 120 mg thrice daily was assessed by an objective protocol. Twenty-five patients with ischaemic heart disease were subjected to serial, measured multistage treadmill exercise without any drugs, and after propranolol 40 mg t.d.s. for 3 days to assess the stress response to beta-blockade. The tests were repeated after 2, 4 and 8 weeks of verapamil. The assessment was based on computerized ST segment changes, the anginal threshold and other objective parameters. Verapamil rendered eight out of thirteen symptomatic patients pain free and significantly increased the anginal threshold in all others. The ischaemic response as assessed by the ST segment changes on exercise showed a marked improvement in the symptomatic as well as the asymptomatic groups. No major side effects were encountered throughout the study. It was concluded that verapamil in a dose of 360 mg/day is an effective antianginal agent free from significant side effects.