OBJECTIVE: To investigate the protective effects of fibronectin (Fn) on vascular endothelial cells. METHODS: Block reticuloendothelial system model compound with injury of tail vein and femur fractures in rats were used. The level of plasma Fn and surface Fn of peritoneal macrophage cells, the numbers of circulating endothelial cells and the injured tail vein were observed. RESULTS: Fn increased the level of plasma Fn and peritoneal macrophage cells surface Fn,but decreased the number of circulating endothelial cells after infusing Fn 1.7 mg/10 g before injury. Under the scanning electron microscope, only a local focus injury to vascular endothelial cells in the rats was observed after Fn was infused, but a piecemeal injury and detachment of vascular endothelial cells were observed in rats without giving Fn. CONCLUSIONS: Fn has obvious protective effects on vascular endothelial cells in rats.