Glioblastoma (GBM, WHO grade IV) is the most lethal type of brain tumours. Despite advances in radiotherapy, chemotherapy and surgical techniques, this tumour is still associated with a median overall survival of approximately 1 year. Histopathological features of GBM include nuclear atypia, foci of palisading necrosis, microvascular proliferation and robust mitotic activity. Glioblastoma is one of the best vascularized tumours in humansand its proliferation is hallmarked by a distinct proliferative vascular component. Studies of glioblastoma’s vascularization have cast some light on the role of non-endothelial cells in tumour neoangiogenesis. A characteristic feature of protein CD133 is its rapid down-regulation during cell differentiation, which makes it a unique cell surface marker for identification of stem cells in brain tissue. CD133+ tumour cells are located mainly in perivascular niches. CD133 positive cells were also found in blood vessels wall. The aim of this study was to optimize immunohistochemical staining method to facilitate identification of cells recognized by anti-CD133 antibody in paraffin- embedded glioblastoma tissue sections. In this study, several pretreatments, detection systems, dilution of antibody and time incubation were used. Immunohistochemical staining method in which autoclave, a buffer pH 9.0 and LSAB+System-HRP were used gave the best result.