Hypoxia-inducible factor-1 alpha (HIF-1 alpha) is the major transcriptional factor involved in the adaptive response to hypoxia. The aim of this study was to assess HIF-1 alpha in 22 patients with transitional meningioma (TM) and 26 patients with glioblastoma multiforme (GBM). HIF-1 alpha was assessed using a commercially available enzyme-linked immunosorbent assay-based HIF-1 transcription factor assay. Levels of HIF-1 alpha in TM and GBM were measured using optical density at 450 nm, and median values were found to be 0.35 for TM and 0.37 OD for GBM, respectively. There was no statistically significant difference between the two types of tumor (p = 0.264). These findings indicate that HIF-1 alpha is elevated in both TM and GBM, suggesting that although hypoxia is one of the most important and powerful stimuli for HIF-1 alpha elevation and consequently angiogenesis, other mechanisms may play roles in HIF-1 alpha stimulation in benign brain tumors such as TM. (C) 2007 Elsevier Ltd. All rights reserved.