Traumatic brain injury (TBI) is the leading cause of death and permanent disability in children and adolescents. Although cognitive and behavioural effects have now been reported for all degrees of TBI severity in children, other aspects of functioning which might be related (such as psychosocial adjustment), have been neglected. In the present study the social and behavioural effects of TBI were assessed by comparing 27 TBI children with 27 controls. TBI children demonstrated significantly lower levels of self-esteem and adaptive behaviour, and higher levels of loneliness, maladaptive behaviour and aggressive/antisocial behaviour. These findings confirm the previously demonstrated detrimental effects of TBI on children's behavioural functioning and offer new evidence for the detrimental effects of TBI on children's social functioning.