Objective: Antisocial behavior frequently occurs in families. This study investigated whether autonomic hypoarousal and hyporesponsivity, which have been observed in antisocial individuals of all ages, are passed from fathers to male offspring. Method: The study included 44 boys with early-onset conduct disorder and 36 healthy controls (8 to 13 years old) together with their biological fathers. Resting heart rate and nonspecific skin conductance fluctuations were assessed as arousal measurements, with electrodermal responses and heart rate changes to pictorial stimuli serving as response measurements. In addition, boys and fathers were subjected to psychometric measurements of antisocial behavior. Results: The fathers of boys with CD showed significantly lower electrodermal responses to pictures of either emotional quality than the fathers of controls (p between 0.015 and less than 0.001), and they revealed fewer nonspecific skin conductance fluctuations (p = 0.001). In addition, they reported a more aggressive, hostile, and impulsive behavioral style. Psychophysiological measurements were highly correlated between fathers and sons (p between 0.007 and less than 0.001), and fathers' autonomic responses accounted for group differences in electrodermal responses between boys (p less than 0.001). Conclusions: The fathers of boys with conduct disorder exhibited an abnormal psychophysiological response pattern similar to that of their sons. High father-son correlations in psychophysiological measures raise the question of whether autonomic abnormalities may constitute a biological mediator through which the disposition for antisocial behavior is transmitted within families. (Contains 4 tables and 1 figure.)