To evaluate the efficacy of anipamil, a phenylalkylamine calcium antagonist, in treatment of stable angina pectoris, we performed a randomized, double blind placebo-controlled, cross-over study. Inclusion criteria were (a) stable angina pectoris for at least 2 months, (b) an exercise test with > or = 0.1-mV horizontal or downsloping ST-segment depression limited by angina, and (c) at least 10 attacks of angina pectoris in a single-blind 3-week run-in period. Nineteen patients were randomized to enter the study. In 3-week periods, they received either anipamil 80 mg once daily (o.d.), anipamil 160 mg o.d., or placebo. At the end of each period, an exercise test was performed. The number of angina pectoris attacks was significantly reduced during treatment with anipamil 80 mg (p < 0.05) and anipamil 160 mg (p < 0.001) as compared with placebo. Glycerol nitrate consumption was significantly reduced during treatment with anipamil 80 mg (p < 0.01) and 160 mg (p < 0.001) as compared with placebo. During exercise testing, the load (W) at start of angina was significantly increased during treatment with anipamil 80 mg (p < 0.01) and 160 mg (p < 0.05) as compared with placebo. Heart rate (HR) at 0.1 mV ST-segment depression was increased during treatment with anipamil 80 mg (p < 0.001). Few adverse events were reported.