Brain development has been studied in 44 embryos (gestational age: 5-12 weeks) and three fetuses (gestational age: 14 weeks) obtained from mothers who used alcohol during pregnancy, and compared with a control group comprising 16 cases of comparable ages. In 34 cases out of 47 in the alcohol group (75.5%), features indicative of abnormal morphological brain development were found. In all, nine variants of brain pathology are described. Abnormalities in the formation of the lateral ventricle walls and disorders of the development of the cortical laminae occurred most frequently (70.6% and 57.9%, respectively). When the cases were sorted according to maternal alcohol intake it was found that the children of severely alcoholic mothers (100-500 ml ethanol per day, 4-7 days per week) had abnormal brain morphology in 100% of cases. In those cases where maternal alcohol use was systematic and frequent (100-200 ml ethanol per day, 2-4 times per week), brain pathology was identified in 83.3% of cases. In systematic maternal use of alcohol (100-200 ml of ethanol taken on one day per week), and in episodic use (35-100 ml of ethanol taken on three occasions during pregnancy), 97.3% and 28.5% were affected, respectively.