Physicians should report child abuse cases to decrease the morbidity for abuse and neglected children. Data show declining morbidity among child victims with increased reporting along with a decrease in the average duration of incest at the time of reporting and an increase in the percentage of reports of one-time-only incest rapes. Failure to report gives the abuser time and anxiety enough to victimize another child. Another reason for reporting child abuse is to determine the incidence of child abuse and neglect, which has been underestimated. Only if all suspected cases are reported can the true incidence and spectrum of the problem be appreciated and accurate information be obtained about response to interventions and strategies for preventive intervention. A third reason to report is to make the process of reporting more routine while reducing the stigma. Parents may be more likely to come forward if reporting becomes routine or may be more likely to cooperate with the physician. Physicians can help families by reporting child abuse since they have unique access to the families. Emergency room physicians are in a good spot to identify child abuse cases or abusing parents. Physicians may unwittingly cooperate with disturbed parents by accepting the parents' diagnosis of the child without question. Finally, reporting increases the physician's influence with child protective agencies, whose help will be required in such a complex situation as child abuse. Physicians and protective agenices should refer to each other as resources. An ongoing collaboration involving the family, the physician, and the protective service worker services the child's best interests. Four case examples and 25 references are provided.