[en] To measure the size of normal corpus callosum in each portion using objective and reproducible method with MRI and evaluation of morphological change of corpus callosum by grade of hydrocephalus. Midsagittal T1-weighted MR imaging of the corpus callosum was investigated in 41 volunteers of normal Korean adults and 19 patients with hydrocephalus. Corpus callosum was measured for the anteroposterior length(A), height(B), and the thickness of genu(C), body(D), splenium(E), and the narrowest portion of body(F). And the analysis of morphology and signal intensity of the corpus callosum were also evaluated. Hydrocephalus was graded as mild, moderate, and severe, and comparison of thickness with normal corpus callosum in each portion was done. The mean length and height were 72.3 mm, 28.6 mm in male, and 70.7 mm, 28.9 mm in female. And the mean dimension for C, D, E and F were 13.1 mm, 8 mm, 13.2 mm, 5.2 mm in male, and 12.8 mm, 7.5 mm, 12.3 mm, 5 mm in female. The morphology of normal corpus callosum was 'hook' shaped on midline sagittal T1-weighted image. Narrowing at posterior third portion of body were present on 30 cases(73.2%) and even in thickness of the body in 11 cases(26.8%). The signal intensity of the corpus callosum on midsagittal T1-weighted spin echo image of normal cases was homogeneous hyperintense as compared with cerebral gray matter. In hydrocephalus, A and B were increased and other portions were decreased in thickness. Genu and the narrowest portion of body showed significant difference of thickness according to the grade of hydrocephalus. The mean dimension of all portion of corpus callosum were larger in male than female except for callosal height but not significant statistically with the exception of splenium. Hydrocephalus lead to morphological change of the corpus callosum. Among the portion of corpus callosum, genu and the narrowest portion of the body were thought to be the most sensitive indicators of degree in hydrocephalus