Background: preterm children are at risk of deficits in language, including grammatical skills. The main purpose of this survey was to investigate whether Persian-speaking children born preterm differ in their morphosyntax ability compared to full-term children. Methods: Morphosyntactic performance was assessed in 86 Persian-speaking children (43 healthy preterm and 43 full-term children) aged 4 and 5 years using the Persian Developing Sentence Scoring (PDSS). Participants were matched for age, gender, and gestational age. Results: The healthy preterm children who participated in this study were significantly outperformed by the full-term children in the morphosyntactic evaluation (p<0. 05). Furthermore, their grammatical skills, based on PDSS, were not as developed as 4 to 5-year-old full-term children. Gender, in general, and gestational age had no effect on the PDSS scores of preterm children (p>0. 05). Conclusion: preterm children, regardless of gestational age, are at risk of morphosyntax impairments, which may not be recovered during the normal development. Therefore, grammatical evaluation and treatment seem to be necessary for these children.