Angioplasty in patients with unstable coronary artery disease is associated with higher complication rates compared with patients with stable disease. In this report we describe our results from a group of patients with unstable disease (unstable angina pectoris and postmyocardial infarction) where a strategy of delaying angioplasty for > 5 days after admission was undertaken. Included are 2069 consecutive patients: 1197 treated for stable angina pectoris and 872 treated during admission for unstable angina or myocardial infarction. There was no difference between the two groups in angioplasty success (92.1% stable, 92.3% unstable), failure to dilate without complication (6.4% stable, 6.1% unstable), or in the rate of major complications: death (0.5% stable, 1.1% unstable), Q-wave myocardial infarction (0.9% stable, 1.1% unstable), and emergency coronary artery bypass (0.6% stable, 0.3% unstable). The duration of hospitalization following angioplasty was longer in the unstable group (5.6 +/- 8.1 days vs. 4.2 +/- 4.1 days; p < 0.001) because of longer duration of heparin infusion. There was no difference between groups in minor complications such as groin hematoma and pseudoaneurysm, renal failure, or infections. It was concluded that delaying angioplasty in unstable patients for > 5 days after admission is a safe and effective therapeutic strategy for this group of patients. The need for prolonged heparin infusion after angioplasty is increased in unstable patients and thus the duration of hospitalization after the procedure is longer.