Effects of diltiazem of frequency of angina and nitroglycerin (NTG) consumption were studied in 12 patients with variant angina (rest pain with ST elevation). Either diltiazem in two dosage schedules (120 mg/day and 240 mg/day), or placebo was administered in a randomized double-blind program over 10 weeks. Significant decreases in angina frequency and TNG consumption were observed when diltiazem treatment periods were compared to placebo periods. Furthermore, when placebo periods following diltiazem were compared to placebo periods following placebo, significant "carry-over" effect with respect to reduced angina frequency was observed. No patient had an increase in angina frequency or TNG consumption on diltiazem compared to placebo. No "rebound effects" or changes in blood pressure or heart rate were observed. One patient complained of dry mouth on diltiazem. These findings, although in a limited number of patients, suggest that diltiazem is effective in decreasing angina frequency and TNG consumption in patients with variant angina. These encouraging results warrant evaluation of diltiazem in a larger patient population over a longer time period.