From 1973 to 1983 we followed 73 asymptomatic healthy subjects who were discovered to have frequent and complex ventricular ectopy. Ventricular ectopy in these subjects was measured by 24-hour ambulatory electrocardiography, which showed a mean frequency of 566 ventricular ectopic beats per hour (range, 78 to 1994), with multiform ventricular ectopic beats in 63 per cent, ventricular couplets in 60 per cent, and ventricular tachycardia in 26 per cent. Asymptomatic healthy status was confirmed by extensive noninvasive cardiologic examination, although cardiac catheterization of a subsample of subjects disclosed serious coronary artery disease in 19 per cent. Follow-up for 3.0 to 9.5 years (mean, 6.5) was accomplished in 70 subjects (96 per cent) and documented one sudden death and one death from cancer. Calculation of a standardized mortality ratio (Monson's U.S. data, 8th revision) for 448 person-years of follow-up indicated that 7.4 deaths were expected, whereas 2 occurred (standardized mortality ratio, 27; P less than 0.05). A comparison of survival of the study cohort with that of persons without coronary artery disease or with mild disease, patients with moderate disease, and men with unrecognized myocardial infarction showed a favorable prognosis for the study cohort over 10 years. We conclude that the long-term prognosis in asymptomatic healthy subjects with frequent and complex ventricular ectopy is similar to that of the healthy U.S. population and suggests no increased risk of death.