Measurement of various portions of the corpus callosum was performed on magnetic resonance(MR) images of 114 subjects with no known or suspected corpus callosal disorders. Midsagittal T1-weighted images used for measurements and mean diameters of various portions in each age and sex group were obtained. Measures of five portions were made : (A) the anterio-posterior length, (B) the diameter of genu portion, (C) the diameter of splenium, (D) the diameter of and mid-body portion, (E) the diameter of narrow portion at the body of corpus callosum. The mean diameter in each gender group for A, B, C, D, and E were 68.8mm, 12.1mm, 12.3mm, 6.9mm, 4.1mm in male and 69.9mm, 12.0mm, 12.1mm, 6.4mm, 4.1mm in female, respectively. The groups of 0-9 years of both genders showed the minimum mean value in each portion.