Abstract: AIM: To study the effects of matrine on rat aortic endothelial cell injury, rat aortic smooth cell proliferation and release of interleukin-1 from mouse peritoneal macrophages induced by fibrin fibrinogen degradation products(FFDP). METHODS: Rat aortic endothelial cell injury was assayed by lactic dehydrogenase release. Rat aortic smooth muscle cell proliferation was determined by crystal violet staining assay. Interleukin-1 activity was measured by mouse thymocyte proliferation assay. RESULTS: Fibrin fibrinogen degradation products significantly increased the lactic dehydrogenase release from rat aortic endothelial cells, proliferation of rat aortic smooth muscle cells and release of interleukin-1 from mouse peritoneal macrophages. Matrine exerted inhibitory effects on the action of fibrin fibrinogen degradation products. CONCLUSION: Fibrin fibrinogen degradation products may play an important role in atherosclerosis plaque formation, and matrine has protective effects against the atherosclerotic injury.