Primary language impairment (PLI) is developmental language disorder characterized by deviant processes of language comprehension and language production in children. Manifestations of disordered language acquistion depend on the characteristics of language itself so recently the researchers have focused on describing the clinical presentation of PLI in different languages in order to improve the processes of early identification, diagnosis and treatment of the disorder. This research has focused on describing morphosyntactic features of language production in speakers of Croatian with PLI at preschool age because it is oftenly highlighted that morphosyntax is a hallmark of PLI. In this research language and metalinguistic knowledge of morphosyntax in children with PLI have been assessed using tasks from croatian version of The New Reynell Developmental Language Scales which are currently in the process of standardization. Language knowledge has been assessed using three simple syntax tasks (verb morphology and two tasks of agreement) and three complex syntax tasks (wh-questions, relative clauses, non-canonical sentences). Metalinguistics knowledge has been assesed using the grammaticality judgment task. Research sample included two groupes of participants, 28 children with PLI and 28 typically developing children. These two groups were further divided into two groups depending on the chronological age range of the participants (younger, CA 4;01-5;06, and older, CA 5;06- 7;09), so finally there were four groups of participants: younger children with PLI, younger typically developing children, older children with PLI and older typically developing children. Between-group comparison revealed that both younger and older children with PLI achieve significantly lower results in comparison with their chronological age-matched typically developing children on most of the variables included in the research. Specifically, the significant difference was nout found only between older children with PLI and older typically developing children on the verb mophology task. Within-group comparison revealed that, despite the overall lower achievement of children with PLI, these children and typically developing children follow the same trajectory in acquistion of simple and complex syntax structures. Also, it revealed that wh-questions, which are categorizied as complex structures, were less challenging for all participants than the other complex structures and moreover, equally demanding as simple structures. So, the question is would it be more appropriate to place wh-questions in the category of simple structures in this research.