The authors describe their experience with methadone treatment in pregnancy. Thirteen abuser pregnant women were studied under defined obstetrical and toxicological protocol. Newborns were also included in this study. In some cases a complete adherence to therapeutic program, allowing labour under very low methadone dosage (5 mg/day), minimized toxicological neonatal risk. Withdrawal syndrome in newborns was well controlled pharmacologically. The role of the toxicological laboratory during clinical management of drug dependent pregnant women is also discussed.