Twenty high risk patients with severe angina were subjected to balloon angioplasty after instituting percutaneous cardiopulmonary bypass support to enhance the safety of high risk elective coronary angioplasty. All patients had a low ejection fraction, a large amount of viable myocardium perfused by the targeted artery or both (left ventricular ejection fraction < or = 25% in 15 patients). Three vessel disease was present in all. Angioplasty of the only remaining vessel was done in 14 patients, 2 vessels in 5 patients and a sequential graft in 1 patient. Bypass flows ranged from 2.8-4.5 litres. Bypass was discontinued after a mean bypass time of 35 min. Haemostasis was achieved by external clamp compression in 16 patients. The angioplasty was successfully performed in all the patients and the procedure was well tolerated. During the bypass period the pulmonary artery diastolic pressures ranged from 0-8 mm Hg. There was 1 hospital death due to abrupt vessel closure. Two patients required surgical help to repair femoral artery. During the follow up period of 1-12 months, 67% patients have no angina and only 1 has died. Our experience demonstrates the safety and efficacy of percutaneous bypass support in selected patients undergoing high risk coronary angioplasty.