Gliomatosis cerebri is a rare diffusely infiltrating glial tumor involving two or more lobes and is frequently is bilateral. Infiltrative extent of tumor is out of proportion to histological and clinical features. We present a case in which finally the diagnosis of gliomatosis cerebri was made. In this case, computed tomography showed that midline structures were insignificantly shifted to the left, there was a mild dilatation of lateral ventricles more expressed on the right, and no pathologic changes of brain tissue density were found. On magnetic resonance tomography, T2W/SE and T2W/FLAIR images revealed zones of hyperintense signal, spreading with time, through several lobes of the brain with no enhancement on T1W images. Diagnosis of gliomatosis cerebri was suspected, stereotaxic biopsy was performed, and pathological examination revealed changes typical of diffuse glial tumor. In this article, changes typical of gliomatosis cerebri seen in other radiological methods such as computed tomography, magnetic resonance spectroscopy, dynamic contrast-enhanced T2*-weighted magnetic resonance, and positron emission tomography also are discussed.