We examined the relationship between the size of five mid-sagittal corpus callosum subareas (measured with in vivo magnetic resonance morphometry) and hand reaction times at dichotic consonant-vowel monitoring in fifty healthy young adults. Based on the reaction times, interhemispheric transfer times between auditory and motor brain areas were calculated and related to anterior and posterior corpus callosum subarea measurements. We found no relationship between the size of callosal subareas and auditory or motor interhemispheric transfer times. We did, however, find a significant correlation between mean reaction time and total corpus callosum size. Our results suggest that normal variation in callosal size or shape is not related to individual differences in auditory lateralization. Instead, callosal size may be associated with speed of information processing.