We characterize predictors of reinfarction and angina in 403 consecutive men aged 60 years or less who underwent heart catheterization within one month (18 +/- 6 days) after a qualifying myocardial infarction. Angiography showed obstructive lesions (greater than or equal to 50% diameter reduction) in 380 patients. One-, two- and three-vessel disease was found in 143 (36%), 139 (35%) and 98 (29%) patients, respectively. After 57 months of follow-up there were 60 deaths (12%), 41 patients (10%) sustained a new infarction and 210 (52%) had angina. Cox regression analysis selected the number of diseased vessels as the only independent 'predictor of reinfarction; independent predictors of angina were the number of diseased vessels and a history of angina prior to the qualifying infarction. Risk stratification showed the probability of reinfarction at 6 years to be significantly lower (P less than 0.001) in patients with one-vessel disease (12%) than in those with two- (30%) and three-vessel disease (37%). Similarly the probability of angina was also lower (P less than 0.001) in patients with one-vessel disease (51%) as compared to those with two- (72%) and three-(74%) vessel involvement. Thus multi-vessel disease is the main predictor of new non-fatal ischemic events after myocardial infarction.