Congenital deafness is a severe, incurable and hardly correctable inherited disease. Mutations in GCB2 and GJB6 genes are most prevalent causes of deafness and occur in patients with hereditary and sporadic deafness all over the world. Some ethnic groups exhibit high rate of heterozygous carriage of most frequent GJB2 mutations (35delG, 167delT, 235delC). Definite association of hereditary deafness and mutational alterations in genes of connexins 26, 30 and 31 shows high informative value of molecular-genetic methods which diagnose hereditary deafness, carriage of mutations in GJB2, GJB3 and GJB6 genes, provide definite probability of the disease in medico-genetic consulting. Further progress in genetics of hereditary hearing loss will raise efficacy of deafness diagnosis at early stages of fetal development and prevent birth of babies with congenital defects of sound perception.