Background: Long QT syndromes (LQT) are genetic abnormalities of ventricular repo-larization, with an estimated incidence of about one per 10000 births. It is characterized by prolongation of the QT interval in electrocardiogram (EKG) and associated with a high risk for syncope and sudden death in patients. Type of this syndrome is association with congenital deafness. Our objective was to evaluate QT interval in children with congenital deafness.Methods: For 219 patients referred to Imam Khomeini Hospital audiometric clinic in 2011, questionnaire were completed. A total of 23 congenitally deaf children were incl-uded. All patients’ examinations were done by a pediatric cardiologist. Electrocardio-gram is conducted in all children (23 patients) with sever and deep congenital deafness. Then the QT interval was measured based on Bazett’s formula. Echocardiography was also performed in these children to assess left ventricular function and the presence of mitral valve prolapse.Results: The overall patients were two hundred and nineteen children. A total of twenty three congenitally deaf children were included and electrocardiogram was obtained. Three children had obviously prolonged QTc (0.48±0.02) second. The median age of them was 6.1±5 year, the median weight was 18±11.3 kilogram and the median of QT interval was 0.48±0.02 second.Conclusion: The QT interval obtained 0.48±0.02 second. In the present study we found prolonged QT in congenital deafness, thus we recommend to evaluate the electrocardio-gram of children with congenital deafness.