Purpose To explore the Clinicopathology characteristics and diagnostic criteria of gliomatosis cerebri(GC).Methods 2 cases of GC cases were studyed by clinical data, MRI, histopathologic observation and immunohistochemical evaluation, combine with documents to analyze points of diagnosis and differential diagnosis.Results Case 1, male, 43 years old.Under a microscope, it is seen that no normal corticomedullary structure; a star-shaped cell proliferation, slightly higher density, the local group of 3-5 of these cells and nuclei appear mild atypia.Histology can only be considered low-grade astrocytomas.Case 2, female, 55 years old, In the light microscope, it can be seen proliferation of astrocytes to form tumors, density was significantly increased.Nuclei showed round / short spindle, a certain degree of atypia.Part of the proliferation of cells astrocytes, which shows a small amount of fat-cell astrocytoma; other is oligodendrocytes.Combined with the imaging features, this two cases can be diagnosed as GC, WHO grade Ⅲ.Immunohistochemical staining showed thatPositive with GFAP, Oligo-2, S-100; in scattered single cells positive for Neu-u.Ki-67 positive index was 1% in case 1, the positive index of about 10% in case 2.Conclusion: GC is a rare tumor with diffuse growth pattern and poor prognosis.Medicalimageology showed the tumor had involved the cerebral hemispheres of two or more cerebral lobes and mostly grew diffusely.Histopathology can be expressed as low-or high-level astrocyte tumor.Among tumor cells, rnicrovascular proliferation and necrosis are generally absent and mitotic figures are rare.