Hearing loss is the most common congenital disorder. A moderate to profound hearing loss is encountered in 1 to 4 per 1,000 live births, and there is a genetic etiology in 60%. Two hundred and sixty Turkish children with genetic non-syndromic profound hearing loss and 67 healthy controls were screened. The pattern of inheritance was DFNB in 87.5%, DFNA in 9.4%, x-linked in 3.1%, and mithochondrial in less that 1%. The GJB2 gene mutations caused hearing loss in 14.7 to 23.2% of children in Turkey. The 35delG was the most common GJB2 mutation both in sporadic and familial cases. The rate of consanguineous marriage was 12.6%. The overall hearing loss in rate in Turkish population is 0.41%. There are 300.000 people who suffer from hearing loss, and 180.000 of them have genetic hearing loss. There are 1 million GJB2 gene mutant allele carriers and 4 million people carrying a hearing loss allele. Every year 4.000 babies are born with hearing loss, and there is a genetic cause in 2.400 of them.