Using light and electron microscopy, the peculiarities of the formation of brain blood vessel structure were studied at the early stages of brain development in human embryos and fetuses, whose mothers took alcohol during the period of pregnancy. Computer morphometric methods with the application of Scion Image program of image analysis demonstrated that in fetuses subjected to prenatal alcohol exposure, at weeks 11 and 12 of development, the average absolute sectional area of blood vessels in the intermediate layer of the brain was diminished, while blood vessel relative area and number per unit area of section were increased as compared to similar values in control group. The process of differentiation of blood vessels into arterial and venous ones was shown to start since developmental week 10.