Neovascularization is essential for tumour growth and is mediated by physiological substances produced by tumours. Vascular endothelial growth factor (VEGF) is one such potent angiogenic factor. Human gliomas, the most important class of intrinsic brain tumours, express VEGF both in vivo and in vitro. Factors involved in the control of VEGF production by glioma cells are not well known. In this study, we investigated the role of basic fibroblast growth factor (bFGF), epidermal growth factor (EGF), and platelet derived growth factors (PDGF) on VEGF production by four different glioma cell lines in vitro. With the exception of PDGF A/A and B/B in one cell line, all growth factors differentially stimulated VEGF production in all cell lines investigated. These data suggest that VEGF production in human glioma may be regulated by other growth factors which are also known to be expressed in such tumours.