The effects of alcohol on the fetus include a wide range of problems; the complete fetal alcohol syndrome is the extreme end of the spectrum. At critical doses alcohol has the potential for multiple adverse effects on the maternal--placental--fetal system. Variability of outcome probably is related to individual differences in drinking patterns as well as in biologic susceptibility. At Boston City Hospital Prenatal Clinic, therapy was provided for pregnant women who reported drinking heavily. Reduction in maternal alcohol consumption before the third trimester was associated with improved neonatal outcome. The obstetrician's office is a potential site for prevention programs. A 10-question drinking history enables physicians to identify pregnant women at risk. Supportive counseling focused on reduction of alcohol use can be integrated with regular prenatal care. Pregnant women who do not respond promptly should be referred to specialized treatment programs. This strategy has the potential to improve the health of both mother and infant.