The association of child hyperactivity and parental psychopathology was explored by establishing lifetime DSM-III diagnoses and histories of childhood hyperactivity among the parents of boys, aged 7-11 yrs, in five diagnostic groups: attention deficit disorder with hyperactivity (ADDH), conduct disorder (CD), ADDH + CD, emotional disorder (ED) and no disorder (NC). These groups were differentiated by a family history of parental psychopathology or childhood hyperactivity. ADDH + CD, CD and ED groups all had significantly higher rates of parental psychopathology than the ADDH and NC groups, for which rates were similar. Significantly more boys in the ADDH, CD and ADDH + CD groups had family histories of parental childhood hyperactivity than did boys in the ED and NC groups.