160 consecutive CCU-treated AMI patients below 66 yr were investigated for ventricular ectopic beats (VEB) by 6-h telemetry prior to discharge and after 1 yr. During the follow-up year 11 patients died suddenly and 20 suffered reinfarction. By stepwise discriminant analysis three independent prognostic parameters were found: (1) radiologic cardiomegaly; (2) severe VEBs prior to discharge; (3) diabetes mellitus. Previous infarct, angina, functional class II to IV, smoking, higher age and radiologic cardiomegaly were significantly more frequent in patients with VEBs prior to discharge. History of heart failure, functional class deterioration, higher age, male sex, large first infarct, VT or VF in CCU, transmural infarction, radiologic cardiomegaly were more frequent in patients with severe VEBs prior to discharge. VEB severity increased significantly during the follow-up year in survivors without reinfarction. This increase occurred in patients with previous infarction, angina pectoris, higher age and heart failure.