The purpose of this study was to determine the possible morphometrical differences of the corpus callosum between professional musicians and non-musicians. Certain callosal dimensions and areas were measured in 20 professional musicians and compared with 20 age-, sex- and handedness-matched control group by using in vivo magnetic resonance imaging (MRI). Sagittal T1-weighted midsagittal sections were traced with the digitizer and the metric scale of the system was used for the measurements. Results were statistically analysed by independent t test. There were significant differences between the two groups both for the anterior and posterior areas of the corpus callosum. Furthermore, significant differences between the two groups were found in the thicknesses of certain parts of the corpus callosum. Our results support the hypothesis that brain morphology is prone to plastic changes caused by environmental factors.