Introduction:Children with cochlear implants experience problems at all language domains, and have more problems in morpho-syntactic skills than others domains. Considering the importance of morphology and syntax in developing of communication skills of children, this study compared the use of high-frequency morpho-syntactic structures among 4-6 years old children with cochlear implants and typically developing children by use of Photographic Expressive Persian Grammar Test (PEGT). Materials and Methods:The participants were 25 children with cochlear implants and 25 typically developing children aged 4-6 years, who were monolingual speakers of Persian. Children with cochlear implants and the typically developing children were recruited from the three Rehabilitation Centers and Kindergartens of Mashhad city (Iran), respectively. Then, PEGT was performed on each child.Results: A significant difference was observed in mean total test scores between two groups )P<0.05). Also, there were significant differences in all grammatical structures except conditional statement, genitive case and demonstrative pronouns between the two groups (P<0.05). Conclusion:It can be concluded that children with cochlear implants are weaker than typical children in expression of the high frequency morpho-syntactic skills.