Forty five patients aged 40 years or younger were treated with coronary intervention in our institution between 1983 and 1994. This young Japanese population had a strong predisposition to risk factors but did not have extensive disease. These patients underwent 50 elective interventional procedures for angina pectoris or old myocardial infarction and 6 direct balloon angioplasty procedures for acute myocardial infarction. The initial successful result was obtained in 41 of the 45 patients (91%). The mean follow-up was 43 +/- 35 months. Angiographic follow-up was available in 31 of the 41 eligible patients (76%). Angiographic restenosis was seen in 9 of these 31 patients (29%), and in 12 of the 38 lesions (32%) with initial successful intervention. There were no deaths among the successfully treated patients. Event-free survival rate without death, myocardial infarction, or coronary artery bypass surgery was 94%; however, event-free survival rate without death, myocardial infarction, coronary artery bypass surgery, or repeat intervention was 66% at 43 months. Ninety three percent of the eligible patients were free from angina at follow-up. These short- and long-term results suggest that young Japanese patients can be treated safely and effectively with coronary interventions.