Intra-aortic balloon counterpulsation (IABP) was performed in 225 patients over a 12-year period for the treatment of severe left ventricular failure following acute myocardial infarction and cardiac surgery, and which had failed to respond to conventional therapy. Of these patients, 97 (43%) were discharged alive from hospital. Patients were followed-up for a mean of 5.8 years (3 months to 11 years) and assessment of functional status was made. In patients with shock after myocardial infarction, the most favourable outcome was seen in patients who had mechanical cardiac defects which were corrected after institution of IABP and in those treated within 8 hours of the onset of shock; of those patients without shock, best results were seen in patients who had evidence of continuing ischaemia prior to IABP. In patients treated after cardiac surgery, long-term results were favourable in patients with good pre-operative left ventricular function and in those who underwent coronary artery bypass grafting or aortic valve replacement. Long-term results in patients treated with IABP for refractory cardiac failure are encouraging and suggest that IABP should have a continuing role in certain high risk patient groups.