BACKGROUND: Childhood hyperactivity has previously been found to be closely connected to subsequent alcohol problems and violent offending among men considered to be without major mental disorders. For others, these associations might be moderated or confounded by other factors, predominantly comorbid conduct disorder. AIMS: The purpose of the study was to investigate aspects of childhood hyperactive behaviour in relation to alcohol or violent offences in adult life, taking the possible confounders of early criminality and aggressive behaviour into account. Method A total of 192 young male law breakers and 95 non-criminal controls were followed from age 11-14 years into their thirties. Information on aspects of hyperactivity, aggressive behaviour, early criminality and later offences was included in the analyses. RESULTS: The results supported the hypothesis that aspects of childhood hyperactive behaviour were significantly associated with later drinking offences and violent offending. Further analyses revealed attention difficulties to be the component of hyperactivity most contributing to the relationship. When taking possible confounding variables into consideration, attention difficulties were related to subsequent violent offending among boys with early criminality, independently of early aggressive behaviour. Early criminality, attention difficulties and aggressive behaviour, however, often co-occurred in the same individual. Subsequent drinking offences or violent offending appeared seven times more often among individuals with all early behavioural problems as compared with those who had no such problems. CONCLUSION: Complex antisocial behaviours in adult life commonly represent persistence of complex childhood behavioural difficulties, but among young law breakers there does appear to be a subgroup of boys with a main problem of attention difficulties who go on to violent offending, even in the absence of early manifestation of aggression.