Cortical dysplasia is a cause of intractable epilepsy and a candidate for surgical resection to control epileptic attacks. The neuronal cytomegaly and balloon cell change are the diagnostic hallmarks of cortical dysplasia. Little research has been performed about the normal-sized dysplastic neuron which has complex arborizing dendrites and lacks in its polarity. The aim of this study was to define the histopathologic characteristics of the neurons in cortical dysplasia. Twelve cases of cortical dysplasia who underwent partial lobectomy for intractable seizures were selected and immunohistochemical staining for NF-M/H, MAP2, tau, and ubiquitin was performed. The perikarya and dendrite of dysplastic neurons were more intensely labeled with antibodies for the high and medium molecular weight neurofilament proteins (NF-M/H) than normal neurons. Immunoreactivity with the MAP2 antibody expressed mainly within the somatodendritic regions was present in the dysplastic or normal neurons without any significant difference in intensity. The complex arborizing dendrites of dysplastic neurons were easily identified due to pronounced immunoreactivity within the somatodendritic regions. Immunoreactivity with the primary antibody against tau and ubiquitin was present in the normal-looking neurons as well as the dysplastic neurons. This study suggests that the dysplastic neurons in cortical dysplasia are accompanied by changes of cytoskeletal neurofilaments, and the immunohistochemical stains for NF-M/H, MAP2, tau, and ubiquigin are useful to detect them.