PurposeThe purpose of this paper is to investigate the relationship between resting heart rate (RHR) and psychopathy. The literature on heart rate vs criminality (including violence) is quite clear; low RHR is associated with engaging in violent and criminal behavior. However, results are not as consistent for psychopathy.Design/methodology/approachThis paper analyzes heart rate measured at ages 18 and 48, and psychopathy at age 48, in the Cambridge Study in Delinquent Development (CSDD). The CSDD is a prospective longitudinal study that has followed 411 boys from childhood to middle age, and measured social and biological factors of interest to the field of criminal psychology.FindingsInterestingly, it was only heart rate at age 18 that was negatively and significantly related to psychopathy at age 48. No trends or relationships were found between heart rate at age 48 and psychopathy at age 48. The findings do, however, indicate that low heart rate at age 18 predicts psychopathy at age 48, and the strongest negative relationships are found between low heart rate (beats per minute) and impulsive and antisocial psychopathic symptoms.Originality/valueThis is the first ever longitudinal study showing that low RHR predicts later psychopathy. Suggestions for future research are outlined.