A common feature of autism spectrum disorder (ASD) is language impairment. But the existing similarities and differences of language impairment among autistic children worldwide have not been thoroughly analyzed. Recognizing such similarities and differences can lead to possible interventions designed for autistic children to target their specific language deficits and help them to communicate more efficiently. This study is an attempt to explore similarities as well as differences between Persian and English languages. It starts with a review of research, which was conducted mainly among English-speaking children and proceeds with a qualitative research (including semi-structured interviews and focus groups with specialists as well as children's mothers) conducted in a center for treatment of autistic disorders in Iran. The result reveals that Persian-speaking autistic children like English-speaking ones suffer from grammatical, pragmatic and verbal-sematic deficits, but certain differences can be noticed due to the linguistic differences between languages. The existing differences are specifically in the realm of grammatical deficit which itself is comprised of tense problems, subject/verb agreement problems (since Persian is a pro-drop language) and misuse of diectic terms. These three areas are further elaborated via relevant examples.