Prenatal diagnostics of genetic diseases becomes more and more popular. Classic obstetric approach for diagnostics of numerous genetic diseases employs biopsy or amniotic liquid analyses. Good evidence now exists that polymerase chain reaction (PCR) is one of the most powerful tools of prenatal diagnostics. In contrast to ultrasound investigation PCR is absolutely safe for an embryo and is much more sensitive at early stage of gestation. PCR analysis can recognize male fetal DNA in mother blood and detect some gender-related genetic diseases. Using detection of Y-chromosome in peripheral blood we have analyzed a diagnostic value of some markers sites of Y-chromosome during gestation, type of blood sample (whole blood, plasma or serum) and varioations of the PCR-method (single-step PCR or nested PCR). Comparative analysis of DNA sequences using NCBI Blast we have found Y-chromosome sites (loci DYS14 and ZFY) suitable for PCR identification of male DNA. Blood plasma is the most optimal blood sample for PCR prenatal gender determination. Prenatal gender determination by PCR can be diagnosed at 4-6 weeks gestation.