Background and Aim: Theory of mind as a cognitive component is the foundation of our ability to explain or predict the behavior of ourselves and others which is done through the attribution of mental status. This ability damaged in deaf children and its development is fast in girls. The aim of this study was to study theory of mind in 5-6 years cochlear implant children and its relation with gender and age of cochlear implant (CI).

Materials and Methods:  This study is descriptive and cross-sectional. Eighteen Farsi speaking children CI children and 18 normal development children aged 5-6 were participated in this study. The normal children were selected from living area of CI children. They were selected through available and easy sampling method. These children had no sensory or speech disorders. The basic theory of mind was tested in these children.

Results: Theory of mind was significantly different in both groups (p = 0.00). The comparison between girls and boys did not show significant difference in normal (p= 0.321) and CI children (p =0.231). There was no significant relationship between the age at CI and theory of mind scores (p=0.100).

Conclusion: Hearing impairment has influence on basic theory development in CI children. Age of implantation and gender had no effect on development of theory of mind.

Keywords: Theory of mind, Cochlear implant, Farsi language.