Objective: To assess whether antisocial children are characterized by low heart rate. Method: A meta-analysis was conducted on 45 independent effect sizes of the resting heart rate-antisocial behavior relationship obtained from 40 studies meeting inclusion and exclusion criteria. Studies were conducted between 1971 to 2002 using a total of 5,868 children. A secondary meta-analysis was also conducted on heart rate during a stressor. Results: Significant overall effect sizes were found for both resting heart rate (d = -0.44, p < .0001) and heart during a stressor (d = -0.76, p < .0001). Gender, age, method of recording, use of psychiatric control group, recruitment source, concurrent versus prospective nature of testing, and source of behavioral rating all failed to moderate this relationship Conclusions: Low resting heart rate appears to be the best-replicated biological correlate to date of antisocial behavior in children and adolescents. Several theoretical interpretations of this relationship are outlined that should be examined in future studies.