Despite the fact that the teratogenic effects of phenytoin have been suggested in several case reports, the evidence for a possible oncogenic potential of phenytoin has not been widely recognized. Recently, neuroblastoma as well as other neuroectodermal and non-ectodermal tumors has been seen in several children exposed to phenytoin prenatally. Previous cases have been almost uniformly associated with the features of "fetal hydantoin syndrome" and none have been developmentally normal. We report a developmentally-normal boy of 21/2 years with an abdominal neuroblastoma whose mother had been on phenytoin (as well as carbamazepine) throughout gestation. We review the various neoplasms which have been reported in the offspring of mothers receiving phenytoin.