Background and Aim: Several recent studies have suggested that young children who stutter tend to show depressed lexical performance relative to peers. Children who stutter was produced fewer total verbs and fewer different verbs than peers did, but these differences can not be attributed to increased general all-purpose verb use. Production of gap verbs was similar between the groups. The fact that the children who stutter produce significantly fewer verbs in their samples relative to peers and overall lexical diversity would be impacted by children who stutter producing fewer total and fewer different verbs. Likewise, if children who stutter produced fewer verbs than peers did, mean length utterance should be impacted, as well due to challenge in learning verbs in children it is important to assess lexical diversity in children. 

Material and Methods: This research was a descriptive-analysis study and cases was selected in speech therapy clinics that conducted on 57 non-stutter children and 13 stutter children (primary school).Due to effects of some distortion factors on the frequency of core vocabulary, we have some exclusion criteria such as: neurological disorders, language disorder, color blinded and etc. The qualified subject entered the test. Then stutter's children implemented 100 words test to access in percent and severity of stuttering. Comparison of frequency of core vocabulary implemented   by word articulation test and word perceptive test and we register frequency of perceptive and expressive vocabulary in noun, verb and adjective category.

Result: The result of this study reveal that mean of frequency of expressive and receptive vocabulary in noun category in stutter children is lesser than non stutter children. There was significant difference between stutter children and non stutter children in frequency of expressive and receptive vocabulary in noun category.  The mean of frequency of expressive and receptive vocabulary in adjective category in stutter children is lesser than non-stutter children. There was not significant difference between stutter children and non stutter children in frequency of expressive and receptive vocabulary in adjective category.  The mean of frequency of expressive and receptive vocabulary in verb category in stutter children is lesser than non-stutter children. But there was not significant difference between stutter children and non stutter children in frequency of expressive vocabulary in verb category. There was significant difference between stutter children and non stutter children in frequency of receptive vocabulary in verb category.

Conclusion: :The results of this research indicate that  frequency of expressive and receptive vocabulary in noun category in stutter children is significantly lesser than non-stutter children and stutter effect on frequency of expressive and receptive vocabulary in noun category. The frequency of expressive vocabulary in verb category in stutter children was not significantly lesser than non stutter children but frequency of receptive vocabulary in verb category in stutter children is significantly lesser than non stutter children and stutter effect on frequency of receptive vocabulary in verb category. The frequency of expressive and receptive vocabulary in adjective category in stutter children was not significantly lesser than non stutter children and stutter does not effect on frequency of expressive and receptive vocabulary in adjective category.