Myocardial ischemia may cause severe cardiac arrhythmias. In the present study, the influence of revascularization on ventricular arrhythmias was investigated. A total of 68 patients (61 male, 7 female; mean age 53 years) with coronary artery disease was divided into three groups: Group A (21 patients) underwent percutaneous transluminal coronary angioplasty (PTCA); Group B (37 patients) had coronary artery bypass grafting (CABG); and Group C were 10 patients who served as controls, who had simple coronary angiography. All patients had a Holter ECG on the day before angiography. PTCA patients and controls were restudied on the day after the procedure, while in Group B, Holter ECG was repeated three weeks after surgery. Groups A and B were again studied 18 months after the first Holter ECG. The PTCA group showed a slight reduction in complex arrhythmias immediately following PTCA, which increased again after 18 months; the CABG group, however, revealed a significant increase in complex arrhythmias three weeks after bypass surgery, but a decrease after 18 months. There was no significant change in the control group before or after angiography. Thus, successful revascularization has no influence on ventricular arrhythmias after 18 months.