Measurement of various portions of the corpus callosum was performed on magnetic resonance(MR) images of 114 subjects with no known or susperted 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-portions length, (B) the diameter of genu portion, (C) the diameter of splenium, (D) the diameter of 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.