The article is devoted to the methodology of prenatal gender selection and ethical aspects of its implementation. Based on the analysis of scientific publications, the principal techniques to determine sex in pre-implantation period, in the embryo and fetus, are presented. Invasive and non-invasive procedures of prenatal diagnosis are descreibed. Invasive procedures include examination of the fetus by chorionic villus sampling karyotyping of cells obtained by amniocentesis. Non-invasive techniques related to pregnant women's blood biochemistry, ultrasound markers of the Down syndrome are given. Fetal blood DNA testing is a more sensitive diagnostic parameter that reduces the indication for invasive procedures. The newest most effective method of sex determination in pre-implantation period is sperm separation screening. Medical and non-medical reasons for prenatal gender determination such as prevention of X-linked genetic disorders in a child, a couple’s choice in order to balance sex of children in the family, social gender preferences are shown. Gender selection for the prevention of the X-linked disorders is justified. Ethical issues regarding to the balance of children in the family, giving preference to a certain sex with the help of advanced diagnostic techniques, and selective abortion are discussed. The bioethical principles for the prevention selective abortion resulted from the gender reasons are established. International documents – the Convention for the Protection of Human Rights and Dignity of the Human Being with regard to the Application of Biology and Medicine, the Declaration of the World Medical Association regulating protection against sexual discrimination are considered