Retrospective analysis of 40 infants born to heroin addicted mothers revealed that 85% developed withdrawal symptoms consisting of central nervous system, gastrointestinal and respiratory disturbances, some within hours of their birth. Respiratory depression at time of delivery was not a prominent feature of these children, suggesting that even in utero, tolerance to chronic narcotic usage develops. A high incidence of low birth weight infants noted by previous authors is substantiated by our study. More than half of these infants were small for gestational age infants rather than true premature infants. Although the morbidity was high, the mortality was limited to two infants both below 1,000 gm birth weight. Serious congenital malformations were not noted in our study. Withdrawal symptoms were also observed in infants born to methadone-maintained mothers. These infants exhibited a withdrawal pattern consisting of central nervous system, gastrointestinal and respiratory disturbances. Pediatricians should be aware that infants born to methadone maintained mothers may be seriously compromised in the newborn period.