Introduction: Wilms’ tumor 1gene was originally discovered as mutated in nephroblastoma, a common pediatric kidney cancer also known as Wilms’ tumor. This gene’s product alteration was indicating the safety of WT1 immunotherapy as well as a potential therapeutic response to its application in patients with glioma. Goal: Our aim was to further elucidate the role of WT1 as a diagnostic and prognostic marker in brain glioma in neuropathology field. Materials and Methods: In this study, formalin fixed paraffin embedded blocks of 135 patients with brain glioma were selected. After tissue preparation for WT1 immunohistochemical evaluation, 2 tissue preparations were excluded due to unsatisfactory amount of tissue. Therefore, data about tissue specimens from 133 patients were included in statistical analysis. Results: In this study, out of 133 cases, 55 were astrocytomas, 42 were oligodendroglioma, 35 were glioblastoma and 1 was mixed oligoastrocytoma.WT1 immunohistochemistry expression was found in 127/6 (95.5%) samples. For the glioblastoma, WT1-expression significantly increased with patient’s age (p=0.05, table 3). WT1 expression and Ki67 proliferation index had prognostic effect in patients with brain glioma (p<0.05), and low expression mean survival was 48.5 months, high expression survival was 18.4 months respectively. Conclusion WT1 expression in Mongolian patients with brain glioma had significantly associated with several adverse prognostic indicators including high Ki67 proliferation index (high grade tumor) and high expression of WT1 and univariable survival.