BACKGROUND There are numerous diseases that are claimed to have a correlation with AB0 blood groups. Analysis on distribution of blood groups in primary brain tumors and clinical value has revealed conflicting results. The purpose of this study is to evaluate the association between AB0 blood groups and glial neoplasms (GN) and their effects on prognosis. METHODS A retrospective cross sectional study was performed. Patients admitted between 2000-2014 and had a diagnosis of GN were evaluated. Blood groups of patients were analyzed and compared with the National blood group data obtained from Turkish Red Crescent Society. The prognostic significance of AB0 blood groups was analyzed within glioblastoma multiforme (GBM), anaplastic astrocytoma and grade 1-2 astrocytoma. RESULTS 759 patients with a diagnosis of glial neoplasia were evaluated. Distribution of AB0 blood groups in the different grades of Glial neoplasia was similar with the national blood group frequencies. There was not a statistically significant difference between grades of glial neoplasia and healthy control patients. Median overall survival (mOS) of GBM patients were 12.9 months in A (95% CI, 10.2-15.5), 13.4 months in B (95% CI, 7.3-19.5), 5.7 months in AB (95% CI, 0.8-10.6), 12.8 months in 0 blood groups (95% CI, 8.6-16.8) (p = .46). mOS of anaplastic astrocytoma patients were 24.4 months in A (95% CI, 15.2-33.6), 47.2 months in B (95% CI, 9.9-84.5), 37.8 months in AB (95% CI, 10.2-80.3), 29.2 months in 0 blood groups (95% CI, 21.2-33.4) (p = .96). mOS in grade 1-2 were 84.2, 90.6 and 144 months for A, AB and 0 blood groups respectively. CONCLUSIONS In our patient group, when compared with general population, there seems to be no association between frequencies of AB0 blood groups and Glial Neoplasia. In addition, the AB0 blood groups have no prognostic impact on glial neoplasms.