Vascular endothelial growth factor (VEGF) is a mitogen for endothelial cells. We have studied the production of VEGF by human pericardial mesothelial cells. Mesothelial cells were separated by scraping the pericardial surface during cardiac surgery and cultured. When stimulated with interleukin (IL)-1α, pericardial mesothelial cells expressed VEGF mRNA and protein in concentration- and time-dependent manners. Hypoxia was also found to enhance mesothelial VEGF mRNA expression. The cells expressed mRNA for Flt-1 (VEGF receptor 1) and Flk-1 (VEGF receptor 2), and exogenous VEGF was found to have migration-promoting activity on cultured cells. We conclude that pericardial mesothelial cells express VEGF, which may serve as an autocrine growth-regulatory mechanism.