Among 1739 male survivors of myocardial infarction, mortality over 5 years was examined in relation to presence of complex ventricular premature complexes (R on T, runs of two or more, multiform or bigeminal complexes) identified during 1 hour of monitoring. Such arrhythmia was associated with excess risk of death over the entire period. Men with R on T or runs during the hour show a 5-year sudden coronary death rate of 25%, compared with 6% of men free of premature complexes. Men with complex ventricular premature complexes are also at relatively higher risk for nonsudden cardiac death than the other men (5-year mortality 15% and 7%, respectively), but no additional disadvantage was associated with the presence of R on T or runs. Multivariate survival analyses, controlling simultaneously for other important clinical factors, identify complex ventricular premature complexes as the strongest influence on risk of sudden coronary death and congestive heart failure as the strongest influence on risk of other cardiac death.