Tehran University of Medical Sciences Auditory and Vestibular Research 2423-480X 22 1 2017 07 31 58 66 Rezvan Akbari Mani Department of Speech therapy, School of Rehabilitation, Tehran University of Medical Sciences, Iran Nahid Jalilevand Department of Speech therapy, School of Rehabilitation, Tehran University of Medical Sciences, Iran Ali Ghorbani Department of Speech therapy, School of Rehabilitation, Tehran University of Medical Sciences, Iran Mohammad Kamali Department of Rehabilitation Management, School of Rehabilitation, Tehran University of Medical Sciences, Iran Mohammad Reza Razavi Department of Linguistic, Academy of Persian Language and Literature, Tehran, Iran 2017 05 30 Background and Aim: Studies have shown that most children before age 4 are able to comprehend and express wh-question. In the Persian language, a case study has confirmed these results. The aim of this study is to evaluate the ability of 4-6 year olds to comprehend and express wh-question. Methods: Seventy two 4-6 year-old Persian-speaking children were selected randomly. Wh-words consist of: what, where, who, why, and when. In the part of comprehension subjects answered questions about two pictures, and in the part of expression they asked questions elicited by a speaking puppet about four pictures. Descriptive analysis and student’s t-test were used for data analysis. Results: In comprehension 4-6 year-old children gained the complete score (2) with SD=0 in all whwords. However, 4-5 year old children gained the score of 1.89 with SD of 0.32 for the word when. In expression, independent t-test showed the maximum score of 3.52 with SD of 0.84 related to questions with who. 5-6 and 4-5 year old subjects had significant differences in questions with what (p=0.005), where (p=0.003), who (p=0.012), and when (p<0.001). Most errors were expressed in question with when. Conclusion: Subjects of this study had the ability to comprehend and express wh-words. Comprehension of wh-words is easy for 4-6 year-old children; they are able to use them in questions, but have some application errors. https://avr.tums.ac.ir/index.php/avr/article/view/334