Hyperactive, psychoneurotic, and normal control boys and their families were examined for minor physical anomalies (MPA). The results revealed that the hyperactive boys and their families had more MPA than the combined group of psychoneurotic and normal control children and their families. There were no differences in the mean number of MPA within families. Hyperactive probands also had more pre- and perinatal complications than the combined proband group. Furthermore, it was quite evident that the combination of numerous obstetrical complications and a high number of MPA significantly increased the probability of a child being diagnosed as hyperactive. The results are discussed in relation to the genetic transmission of MPA and the use of MPA as high risk indicators.