We examined the expression of vascular endothelial growth factor (VEGF) protein, p53 protein, and the MIB-1 index in 43 patients with malignant gliomas in relation to tumor vascularization by an immunohistochemical method. Factor VIII-related antibody was employed for the evaluation of the vascularity and endothelial proliferation. Of the 42 cases of malignant gliomas, 36 (86%) demonstrated immunoreactivity for VEGF in their tumor cells, whereas 22 (52%) had VEGF in their endothelial cells. There was a tendency for the vascularity to be correlated with the immunoreactivity for VEGF (coefficient, 0.340). In addition, a marked increase in endothelial proliferation was evident in cases showing moderate to strong positivity for VEGF as compared with the others. Immunoreactivity for VEGF was found mostly in the malignant gliomas without p53 overexpression and/or with p53 overexpression. However, statistical analysis revealed a correlation between the grade of p53 overexpression and the grade of VEGF expression (coefficient, 0.507), but not between the VEGF and MIB-1 index in our series. There was a tendency for the MIB-1 indices to increase in correlation with increasing vascularity.