OBJECTIVES: To determine the effects of atenolol, nifedipine and their combination on exercise parameters and ambulatory ischaemic activity in patients with mild chronic stable angina. SETTING: Multicentre, multinational study involving 608 patients from 69 centres in nine countries. DESIGN: Placebo washout followed by double-blind parallel-group study comparing atenolol 50 mg bd, nifedipine SR 20 mg bd, and their combination. Patients underwent maximal exercise testing using either a bicycle (n = 289) or treadmill (n = 319) and 48 h of ambulatory ST segment monitoring outside the hospital environment at the end of the placebo washout period and after 6 weeks of active therapy. RESULTS: Both medications alone and in combination caused significant improvements in exercise parameters and significant reductions in ischaemic activity during daily activities, when compared with placebo. There were, however, no significant differences between groups, for any of the measured ischaemic parameters although combination therapy resulted in a greater fall in resting systolic and diastolic blood pressure than either treatment alone. CONCLUSIONS: In the management of mild chronic stable angina there appears to be little advantage gained from using combination therapy for ischaemia reduction.