Background: This article selectively reviews the biological bases of antisocial and aggressive behavior in children with a focus on low autonomic functioning, prefrontal deficits, and early health factors. Results: Low resting heart rate is thought to be the best-replicated biological correlate of antisocial and aggressive behavior in child and adolescent populations and may reflect reduced noradrenergic functioning and a fearless, stimulation-seeking temperament. Evidence from neuropsychological, neurological, and brain imaging studies converges on the conclusion that prefrontal structural and functional deficits are related to antisocial, aggressive behavior throughout the lifespan. A prefrontal dysfunction theory of antisocial behavior is advanced. This argues that social and executive function demands of late adolescence overload the late developing prefrontal cortex, giving rise to prefrontal dysfunction and a lack of inhibitory control over antisocial, violent behavior that peaks at this age. Birth complications and minor physical anomalies are selectively associated with later violent behavior, especially when combined with adverse psychosocial risk factors for violence. Cigarette smoking during pregnancy may increase the risk for antisocial and violent behavior in later life by disrupting noradrenergic functioning and enhancement of cholinergic receptors that inhibit cardiac functioning. Malnutrition during pregnancy is associated with later antisocial behavior and may be mediated by protein deficiency. Conclusions: It is argued that early health intervention and prevention studies may provide the most effective way of reversing biological deficits that predispose to antisocial and aggressive behavior in children and adults.