Many patients with angina pectoris whose symptoms are not completely controlled by beta-blockers are treated with several types of drugs, but it is not clear whether addition of a calcium-channel antagonist and/or a nitrate confers any advantage over beta-blockade alone. 18 patients receiving atenolol for stable angina pectoris completed a double-blind, randomised, crossover trial of atenolol treatment plus placebo, isosorbide mononitrate, nifedipine, and mononitrate and nifedipine (triple therapy). The patients were assessed subjectively and by treadmill exercise testing and 24 h ambulatory electrocardiographic recordings at the end of each 4-week treatment period. There were no significant differences among the treatment periods in angina attack rates, glyceryl trinitrate consumption, exercise duration to onset of angina or 1 mm ST depression, or duration of symptomless ischaemia. Total exercise duration was longer on atenolol plus mononitrate than on atenolol alone (mean difference 46 [95% confidence interval 18-88] s; p = 0.005), atenolol plus nifedipine (36 [2-71] s; p = 0.04), or triple therapy (28 [6-61] s; not significant). In 12 patients the exercise time was shorter on triple therapy than on atenolol plus mononitrate alone. Although "maximum" antianginal treatment with two or three drugs is commonly accepted, this approach confers no substantial advantage over optimum beta-blockade as monotherapy. If a second drug is needed, there is a slight advantage in favour of isosorbide mononitrate, but if this is not effective, treatment should be changed rather than added. Many patients with angina pectoris seem to be pharmacologically overtreated.