Background and Aim: The purpose of the present research is to investigate the relationship between syntactic complexity (in terms of sentence and clause structure) on the stuttering occurrence in pre-school Persian speaking children who stutter (CWS).

Materials and Methods: The present cross-sectional study was carried out on 15 monolingual CWS (12 boys and 3 girls) ranging in age from 4 to 6 years old in Mashhad. The convenience sampling method was used to collect data. The 30 minute spontaneous speech samples were recorded in a quiet room in speech therapy clinic while the child was speaking with the speech therapist or the parent (mother or father). The 60 numbers of the utterances produced by CWS were transcribed and then a paired T-test was used to analyze the data.

Results: The results showed significant differences between fluent and non-fluent utterances in terms of syntactic complexity of sentence and clause structure. The results indicated that at clausal level, by increasing the verb arguments in both the main and subordinate clauses, the stuttering occurrence was significantly increased (P<0.01). Moreover, the stuttering occurrence was higher among the compound sentences compared to the simple ones (P<0.01).

Conclusion: The research findings denoted that there was a meaningful relationship between the syntactic complexity based on sentence and clause structure and the stuttering occurrence in Persian CWS.

Keywords: Syntactic complexity, Sentence, Clause, Verb argument, Stuttering