Systolic time intervals (STI) were measured at rest before and after an exercise training programme in 37 patients with ischemic heart disease; 17 patients were treated with a beta-blocking drug (BB-group) and 20 were not (nBB-group). After the training period peak oxygen uptake had increased by 37% in the BB-patients and by 41% in the nBB-group. During the training period electromechanical systole (QS2) and pre-ejection period (PEP), when corrected for heart rate, shortened significantly in all 37 patients. Left ventricular ejection time (LVET) increased but when corrected for heart rate no significant changes occurred. The ratio of PEP/LVET decreased significantly. The changes in STI were similar in the patients treated with beta-blocking drugs than in those without such treatment. The changes in STI in both groups suggest that left ventricular function improves during the training period and that beta-adrenergic blockade does not alter this outcome.