Angiogenesis is considered to play an important role in the development of malignant brain tumors, especially glioblastoma multiforme (GBM). Abnormal vascular construction with a glomeruloid appearance is characteristic of GBM. beta-catenin is known as one of the adhesive molecules associated not only with cell adhesion and cell polarity, but also with carcinogenesis. We postulated the relevance of beta-catenin to vigorous endothelial proliferation in human GBM because the vascular cells (VCs) are apt to lose their cell polarity. The object of this study is to compare the immunohistochemical localization of beta-catenin in VCs between GBMs and normal brain tissues. Immunohistochemical analysis of beta-catenin for VCs in 32 GBMs and 10 normal brain tissues was performed. beta-catenin was found concentrated in the areas of vascular cell-cell junction and internal surface of the vascular lumen in all normal brains. In contrast, beta-catenin, in proliferating VCs in GBMs, was stained homogeneously and intensely in the cytoplasms of 26 cases (81.3%), in which nuclear staining of beta-catenin was also recognized in four cases (12.5%). In conclusion, the intracellular localization of beta-catenin in VCs of GBMs was found to be different from that of normal brain tissues. The changes of expression of beta-catenin may be associated with the angiogenesis or transformation of the VCs in human GBM.