Seventy patients hospitalized with chest pain after cocaine use were retrospectively evaluated to define the risk and clinical course of acute myocardial infarction (AMI). AMI developed in 22 patients (31%) and transient myocardial ischemia was seen in an additional 9 patients (13%). Coronary risk factors did not distinguish those who developed AMI from those who did not. The presenting electrocardiogram was abnormal in 20 of 22 patients who evolved AMI and in 19 of 48 of those who did not. Creatine kinase levels were elevated in 75% of the patients, including 65% of those who did not develop AMI, but creatine kinase-MB elevations were only observed in the AMI group. The route of cocaine administration did not predict AMI and there was no predilection for a particular coronary vascular bed. The length of time between drug use and onset of AMI pain was often quite prolonged (median interval, 18 vs 1 hour in the non-AMI group). Eight of the patients with AMI underwent cardiac catheterization and 4 had significant coronary narrowing.