Ventricular ectopic beats (VEB) were studied in 100 consecutive patients prior to discharge after an acute myocardial infarction and again after 1 yr, on 6-h recordings. VEB were found in 71 patients prior to discharge. Reinfarction and sudden death taken together were significantly more common in the 35 patients who had severe VEB, i.e. multiform, paired, R-on-T or ventricular tachycardia (P less than 0.05). Reinvestigation after 1 yr of 73 survivors who had not reinfarcted revealed a nonsignificant overall increase in patients with VEB from 67 to 78% together with an increase in degree of severity. The intraindividual pattern, however, differed considerably. Several clinical findings including angina pectoris, heart fialure, hypertension, diabetes mellitus, hyperlipidemia, antiarrhythmic therapy, and smoking, failed to differentiate patients with increasing VEB severity from the remainder.