It has been shown that cardiac enlargement, whether hypertrophic or dilated, is an independent risk factor for sudden cardiac death, although the definition of what constitutes cardiac enlargement is not universally established. This study was designed to address this issue and to determine normal cardiac weights in adult men. A prospective study was undertaken of healthy men dying from sudden traumatic deaths aged 18 to 35 years. Cases were excluded if there was a history of medical illness including illicit drug use; prolonged medical treatment was performed; there was a prolonged period between the time of injury and death; body length and weight could not be accurately assessed; there was significant cardiac injury; or any illness or intoxication was identified after gross and microscopic analysis, including evidence of systemic disease. A total of 232 cases met the criteria for inclusion in the study during the approximately 6-year period of data collection from 2005 to 2011. The decedents had an average age of 23.9 years and ranged in length from 146 to 193 cm with an average length of 173 cm. Their weights ranged from 48.5 to 153 kg with an average weight of 76.4 kg. Most decedents (87%) died of either ballistic or blunt force (including craniocerebral) injuries. Overall, their heart weights ranged from 188 to 575 g with an average of 331 g and an SD of 56.7 g. Regression analysis was performed to assess the relationship between heart weight and body weight, body length, and body mass index and found insufficient associations to enable predictability. The authors, therefore, propose establishing a reference range for heart weight in men, much like those in use for other laboratory tests including hemoglobin, hematocrit, or glucose. A reference range (95% inclusion) of 233 to 383 g for the adult male human heart is proposed.