The action of nifedipine (N), acebutolol (A), and their association (A+N) was studied in 16 patients suffering from effort angina with documented coronary artery disease. The therapeutic action was valued by bicycle effort stress test after oral administration of medications in comparison with placebo (P), following a double-blind random sequence of treatments. Working capacity significantly increased after A (507 ± 450 mkp, p < 0.05), after N (1,140 ± 767 mkp, p < 0.001), and after A+N (1,198 ± 644 mkp, p < 0.01). The increments of work after P administration were not significant. Moreover, fatigue instead of angina appeared as a stopping criterion in 8 patients after A+N, and in only 1 patient after P, A, and N.