Opioid dependent patients often are dependent from the illegal consumption of heroin and, in addition, perform a polytoxicomanic way of consuming drugs. They suffer of various somatic and psychiatric diseases. Moreover, pregnancies of drug addicted women are classified as high-risk pregnancies. With respect to the particular consumed drug substances other than opioids during pregnancy variable forms of teratogenic and toxic effects can be assigned to the baby. Critical values of maternal substance abuse referring to fetal impairment do not exist. With regard to the possible teratogenic and toxic fetal effects of maternal consume of alcohol, tobacco, sedativa, cannabis, cocaine and amphetamines, withdrawal treatment of polytoxicomanic pregnant patients under inpatient medical supervision including medication if necessary represent the first-line-treatment. With respect to smoking, it is possible to detoxicate the patients also by an outpatient treatment. However, referring to heroin addiction, a maintenance therapy with L-methadone, D/L-methadone or buprenorphine should be preferred since fetal withdrawal symptoms of opioids otherwise can cause severe complications which even can lead to the loss of the fetus and also increase the risks for the mother. Increasing the dose of the opioid substitute may be necessary, for example, to avoid premature uterus contractions. It is to be pointed out that substitution treatment with methadone or buprenorphine also improve the medicinal compliance and psychosocial circumstances of the pregnant patients. Subsequent to delivery, the maintenance treatment should initially be pursued over a further period of time. In the follow up, the question of continuing with maintenance treatment or starting a withdrawal treatment of opioids should be discussed on an individual basis. To sum up, proceeded interdisciplinary care during pregnancy and afterwards by all the professions involved like general practioners as well as social workers, gynaecologists, paediatrists, pharmacists, psychologists and psychiatrists should be ensured. Futhermore, diagnosis and therapy of the comorbid psychiatric and infectious diseases like hepatitis A, B, C and HIV are necessary and described (see Part II. Comorbidity and their treatment).