Opioid dependence has been studied with regard to its effects on the woman, the fetus, and the child for the past three decades, and it continues to be a serious problem that must be recognized and addressed by the health care delivery system in order to provide optimal medical care. The use of pharmacotherapy, such as methadone maintenance treatment (MMT), is only one of a variety of treatment modalities to provide optimal services for opioid-dependent women. The complete schema for treating opioid dependence in the perinatal period is complex and intense, but MMT serves multiple purposes. Primarily, it removes the addicted woman from the drug-seeking environment, eliminates the necessary illicit behavior, and prevents the peaks and valleys in the maternal heroin level that may occur throughout the day. In addition, maternal nutrition is usually improved and MMT patients become amenable to prenatal care and psychosocial rehabilitation. It is evident from the findings of numerous studies that when the physical, psychological, and socioeconomic issues of pregnant opioid-dependent women and their children are coupled with MMT, the potential physical and behavioral effects of psychoactive drugs on the mother, the fetus, the newborn, and the child may be markedly reduced.