Objective: Genetic studies show that consanguineous marriage can increase the probability of incidence of genetic impairments such as hearing impairments. The target of this study is to identify the prevalence of consanguinity among the parents of hearing impaired students in primary schools.

Materials and Methods: We selected all of deaf students of Tehran (614 students). Their mothers answered to questionnaires. The questions were about Risk Factors of deafness in mother pregnancy or in neonatal period.
Results: from 614 students, 389 parents of them (64%) had consanguineous marriage and 223 person (36%) didn&apost have this factor. 2 person did not answer to this question. In this study we observed that there is 32.3% family history of hearing loss, 29.2%deaf sister and brother, 17% ear infection history. Other risk factors were studied too. Also there is significant correlation between consanguinity and more than one deaf children in the family (p<0.005).
Conclusion: According to high incidence of consanguinity (64%)that was observed in this study it may be one of most important causes of sensory neural hearing loss in children, so we should give enough information about this problem to the people.