The clinical effects of nitrendipine, a new calcium antagonist, were investigated in a single-blind test on 21 patients with variant angina pectoris. The efficacy of the drug was evaluated on the basis of frequency of anginal attacks and Holier electrocardiographic findings during different treatment periods at doses of 10mg once a day (period I) and 20mg once a day (period II). The number of anginal attacks decreased significantly from a pretreatment level of 2.1±0.3 per day to 0.7±0.2 per day in treatment period I and 0.3±0.1 per day in treatment period II (p<0.01, p<0.001, respectively). The consumption of sublingual nitroglycerin tablets decreased significantly in both treatment periods in comparison with the observation period before treatment (p<0.01, p<0.001, respectively). In 20 patients with continuous ECG monitoring, the frequency of ST-segment elevation was 4.5±1.0 per day during the pretreatment period; it decreased significantly to 0.9±0.6 per day in treatment period I and 0.5±0.3 per day in treatment period II (p<0.01, p<0.001, respectively). The duration and the maximum magnitude of ST-segment elevation also improved significantly in both treatment periods. These results demonstrate the efficacy of nitrendipine in the treatment of variant angina at a single daily dose of 10mg.