['To test the hypothesis that increasing levels of hypoxia are associated with increased expression of vascular endothelial growth factor (VEGF) in prostate cancer by correlating the level of median tissue oxygenation in human prostate tumors with the immunohistochemically determined level of VEGF expression.', 'Custom-made Eppendorf oxygen microelectrodes were used to quantitate the pO(2) levels in prostate tumors of 13 men undergoing radical prostatectomy. All pO(2) measurements were performed under fluorine-based general anesthesia. Paraffin-embedded tumor tissue from these men was analyzed to measure the level of VEGF expression by immunohistochemical staining. The significance of the associations between the pO(2) levels and VEGF staining were determined by the Pearson correlations.', 'The range of the median pO(2) levels (based on between 97 and 129 individual measurements) among 13 prostate tumors was 0.5 to 44.9 mm Hg. The blinded comparison of pO(2) levels and VEGF staining intensity demonstrated a significant correlation between increasing hypoxia and the percentage of cells staining positive for VEGF (r = -0.721, P = 0.005). This correlation was also significant when pO(2) levels were compared with the overall immunoreactive score, which takes into account staining intensity (r = -0.642, P = 0.018).'] Does increased hypoxia correlate with increased expression of the angiogenesis marker vascular endothelial growth factor in human prostate cancer?