Low resting heart rate is a well-replicated physiological correlate of aggressive and antisocial behavior in children and adolescents, but whether low resting heart rate increases the risk of violence and other antisocial and risk-taking behaviors in adulthood has not been studied in representative samples. To study the predictive association of resting heart rate with violent and nonviolent criminality and with fatal and nonfatal injuries owing to assaults and unintentional injuries in the population. We conducted a study of data from several Swedish national registers on 710 264 Swedish men in the general population born from 1958 to 1991, with a follow-up of up to 35.7 years. Outcome data were available and analyzed from January 1, 1973, through December 31, 2009. Resting heart rate was measured together with blood pressure at mandatory military conscription testing at a mean (SD) age of 18.2 (0.5) years. Violent and nonviolent criminal convictions and medical treatments or deaths owing to assaults and unintentional injuries. In models adjusted for physical, cardiovascular, psychiatric, cognitive, and socioeconomic covariates, compared with 139 511 men in the highest quintile of the distribution of resting heart rate (≥83 beats/min), 132 595 men with the lowest quintile (heart rate, ≤60 beats/min) had a 39% (95% CI, 35%-44%) higher hazard of being convicted of violent crimes and a 25% (95% CI, 23%-28%) higher hazard of being convicted of nonviolent crimes. The corresponding hazard was 39% higher for assault injuries (95% CI, 33%-46%) and for unintentional injuries (95% CI, 38%-41%). Further adjustment for cardiorespiratory fitness in a subset of 572 610 men with data from an exercise test did not reduce the associations. Similar associations were found between low systolic blood pressure and violent and nonviolent criminality and for assault injuries when systolic blood pressure was studied instead of resting heart rate in more than 1 million men. Among men, low resting heart rate in late adolescence was associated with an increased risk for violent criminality, nonviolent criminality, exposure to assault, and unintentional injury in adulthood. Most of these results were replicated with low systolic blood pressure. Resting heart rate and other autonomic measures merit further study in the development and prevention of violence and antisocial behavior.