effect of bilingualism on volume of corpus callosum

background and aim: in spite of the effect of the left hemisphere domination on first langu­age acquisition in human, studies suggest activi­ties and the role of both hemispheres in learning second language. therefore learning a second language requires more communication between the two hemispheres. regarding the role of the corpus callosum as the only data-centric inter­face between the two hemispheres, the aim of this study was to evaluate and compare the vol­ume of the corpus callosum in monolingual and bilingual individuals. methods: this cross-sectional study was cond­ucted on 24 samples, 16 simultaneous bilinguals (eight kurdish-persian, eight turkish-persian) and eight monolinguals with age range of 18 to 30 years, all right handed, and in equal numbers in both sexes (female and male), volume of cor­pus callosum determined by mri. data was analyzed by parametric and non-parametric sta­tistical tests. results: the volume of corpus callosum is sma­ller in monolinguals in comparison with bilin­guals, in which a significant difference was obs­erved (p=0.04). conclusion: according to the language data transmission and the rate of processing by the corpus callosum between two hemispheres, it seems for improving the quality of aural reha­bilitation, the findings of present study will be useful before performing programs like auditory training, language learning, and by development of neuroplasticity which is often decoded by sti­mulus that occur in the hemisphere in contrast to the dominant hemisphere.