Heart weights of white men 20 to 39 years of age. An analysis of 218 autopsy cases. Review of autopsy data for 218 white men between 20 and 39 years of age who died of injuries or suddenly and unexpectedly indicated a mean heart weight of 371 g. The mean for those dying of external causes was 364 g whereas the mean for those dying of natural causes was 446 g. A coefficient for heart weight expressed as a percentage of body weight was lower in heavy individuals than lightweight individuals; it ranged between 0.38% and 0.55%, with a mean of 0.48%. Heart weight, including epicardial fat, increased with age and body weight. These data may be useful to those who are called upon to investigate sudden and unexpected deaths. 