Astrocytomas are the most common primary central nervous system neoplasms in which the redominant cell type is derived from an immortalized astrocyte. Two classes of astrocytic tumors are recognized, those with narrow zones of infiltration (e.g., pilocytic astrocytoma, subependymal giant cell astrocytoma and pleomorphic xanthoastrocytoma) and those with diffuse zones of infiltration (e.g., low grade diffuse astrocytoma, anaplastic astrocytoma and glioblastoma). Astrocytic tumors are classified into four grades (I-IV) according to the WHO on the basis of cytological atypia, mitotic activity, vascular proliferation and necrosis. Aim of the study To assess the immunohistochemical expression of Ki-67 and PCNA as a proliferative markers to study proliferative activity and CD34 as an endothelial cells marker to study vascular proliferation in astrocytomas in correlation with some clinicopathological parameters (age, gender, site of the tumor and tumor grade). Patients, Materials, and Methods The study is a retrospective one in which a total of fifty one formalin fixed paraffin embedded brain astrocytomas excisional biopsies for the period from June 2009 to February 2011 were retrieved from the archival materials of the specialized surgical hospital in medical city in Baghdad, during the period from January 2011 to April 2011. The histopathological diagnosis had been revised and all cases were stained by immunohistochemical technique with Ki-67, PCNA and CD34 tumor markers. Values were considered statistically significant when P<0.05. Results Concerning the clinicopathological assessment, fibrillary astrocytoma (WHO grade II) was found to be the most common type among astrocytic tumors, the peak age incidence of astrocytomas was found in the second and fifth decades of life and a slight male predominance had been identified. Immunohistochemical expression of Ki-67 had a highly significant correlation with the age of cases (P-value=0.003) and with the grade of astrocytomas (P-value˂0.001). On the other hand, there were no significant correlation between immunohistochemical expression of Ki-67 and gender and the site of astrocytomas (P-value>0.05). Regarding PCNA immunohistochemical expression, there was a highly significant correlation between age and the immunohistochemical expression of PCNA (P-value=0.002), and there was a significant correlation between the immunohistochemical expression of PCNA and the grade of astrocytomas (P-value˂0.001). On the other hand, PCNA immunohistochemical expression had no correlation with the gender, nor with the site of astrocytomas (P-value>0.05(. For the CD34 immunohistochemical expression, there was a significant correlation between immunohistochemical expression of CD34 with the age of cases and histopathological grade of astrocytomas (P-value=0.007), (P-value˂0.001) respectively. No significant correlation between immunohistochemical expression of CD34 and gender and site of the astrocytomas had been found (P-value˃0.05). There was a highly significant correlation between Ki-67 immunohistochemical expression and PCNA immunohistochemical expression in astrocytomas, (P-value˂0.001). Conclusion •A significant correlation has been found between Ki-67 immunohistochemical expression and the clinicopathological variables (age and grade of tumor). Ki-67 immunohistochemical expression can be used as an ancillary parameter to differentiate between border line grades of astrocytomas. •A significant correlation has been found between PCNA immunohistochemical expression and the clinicopathological variables (age and grade of tumor). So PCNA as a marker for proliferation could be used with Ki-67 as an ancillary method in the differentiation of border line grades of astrocytomas. •A significant correlation has been found between MVD (detected by CD34 immunohistochemical expression) and the clinicopathological variables (age and grade of tumor). Hence the MVD detected by the immunohistochemical expression of CD34 as a marker of angiogenesis may be of help in differentiation of border line grades of astrocytomas.