Introduction: The aims of this study are a comparative study of phonological processing in bilingual (Kurdish- Persian) elementary children with Down syndrome in Kurdish and Persian Languages.

Materials & methods: This is a descriptive study in which all bilingual (Kurdish- Persian) elementary children with Down syndrome who are studying in exceptional schools of Ilam city have been participated. They were normal in hearing and oral structure. Standard Phonetic tests in Kurdish and Persian are used to extract phonological processing.  Obtained data have been analyzed by means of SPSS software.

Finding: The result of data analysis shows that there was no significant difference between language function of the patients in Kurdish and Persian languages, and their phonological problems in both languages were the same.  Besides, there was no significant difference between gender and phonological problems in most subgroups of phonological processing, and male and female output were the same, except for the substitution and cluster reduction between boy and girls had significant difference.

In general there was no significant difference between gender, language and phonological awareness.

Discussion & conclusions: An investigation of relationship between type of language, gender and phonological process shows that there is no significant relation between these variables, so the phonological errors may be resulted from deviation.