A survey by the Japanese Coronary Intervention Study (JCIS) group revealed that 109,788 percutaneous coronary intervention (PCI) procedures were performed at 1,023 laboratories during 1997. The present study aimed to describe the demographic and clinical characteristics, treatment strategies, in-hospital outcomes, and long-term outcomes of these patients. A total of 10,642 PCIs performed in 8,814 patients, which corresponded to approximately 10% of the overall PCIs, were selected at random. The mean patient age was 65 years, and 75% were males. The patients often had extensive coronary risk factors. The most prevalent clinical diagnosis was stable angina (36%), followed by myocardial infarction (MI) excluding acute myocardial infarction (AMI; 28%) and AMI (25%). Plain old balloon angioplasty was used as the sole procedure in 58% of lesions for which an attempt to heal was made, and coronary stent placement in 38%. Angiographic success was achieved in 92% of attempted lesions. Mortality, MI and emergency coronary artery bypass grafting (CABG) rates during the hospitalization were 2.6%, 2.0% and 0.7%, respectively. In-hospital mortality rate for AMI was 7.6%, whereas that for elective PCI in cases without AMI was 0.6%. The overall mortality for 1.8 years was 8%. Repeat PCI was performed for 35% and CABG for 6% during the follow-up period. In Japan, PCI was performed in patients with coronary artery disease and extensive risk factors, but a high rate of angiographic success was achieved. The rates of in-hospital mortality and emergency CABG were low in non-AMI patients, but the 1-year rate of repeat PCI was as high as 32%.