Objective: The etiology of deafness can be classified as genetic, acquired and unknown. An unknown etiology was a high incidence in previous reports. The aim of this study is to explore the etiology of deafness and to reduce the cases in the unknown group. Methods: This study was conducted on 162 students at the Yeditepe School for the deaf. Otologic, physical and psychological. examinations were performed by a team of doctors including four otologists, a geneticist, a dentist, an ophthalmologist and an audiologist. Results: A genetic cause was identified in 41.35%, acquired 37.65% and unknown 20.98%. Genetic etiologies were stratified as familial and syndromic subgroups. A familial cause was found in 60 of 162 children and in 22 of those 60 cases, the parents had a consanguineous marriage. There was 11 cases associated with a syndrome. Ninety four minor abnormalities have been established in some deaf children. Febrile convulsion (36%) was identified as the most common etiology in acquired cases. Conclusion: In contrast with other studies the consanguineous marriage was present in 36.6% of the familial cases and 38.8% in total of the school. An unknown etiology was reported in high rates in previous reports. These unknown cases could be described as a part of a syndrome by a crowded team of consultants. Evaluation of early diagnostic criterias and minor abnormalities can help us to provide early rehabilitation of deafness in childhood. Published by Elsevier Science Ireland Ltd.