We reported here 5 cases with the Rett syndrome (RS) who fulfilled the criteria for RS. The changes in CT and MRI findings with the clinical course were studied. Cortical atrophy especially in the frontal area, progressed gradually with the clinical progression after 2 years old in CT. In axial sections on MRI, frontal atrophy was also demonstrated. The white matter, basal ganglia, thalamus and hypothalamus area were all normal. In midline sagittal sections, corpus callosum was hypoplastic, and widening of prepontine cistern and narrowing of the brainstem were demonstrated in some cases. There was no significant atrophy of the cerebellum, amygdala and hippocampus. Follow-up studies including CT and MRI are necessary to evaluate brain morphology in RS.