Male and female sex determination depends on Y-linked SRY gene activity. This gene initiates the cascade of reactions which lead to the differentiation of bipotential, indifferent gonads to testes or ovaries, depending on the presence or absence of active from SRY. Since SRY discovery in 1990, several new genes playing important role in gonadal and in both internal and external genitalia development and differentiation have been identified. Detailed knowledge concerning above mentioned genes will enhance our understanding of etiology of sexual development abnormalities.