Aim To study the changes of serum type I procollagen carboxyl terminal peptide (PIP) and the expression of type I collagen after balloon injury in rabbit and the effects of musk pill (MP) on it. Methods 45 rabbits were divided randomly into three groups: group of angioplasty (AP), group of AP plus musk pill (AP+MP) and group of control. A reproducible rabbit model of atherosclerosis was established with cholesterol feeding after iliac artery injury induced by an inflated balloon and balloon angioplasty was carried out. The expression of type I collagen gene in the smooth cells(SMC) of the iliac artery and serum PIP was respectively observed by molecular hybridization and radioimmunoassay. Results The level of serum PIP increased (9.54±1.49, p<0.05) in AP group compared with in control group. The expression of type I collagen(160±12,p<0.05) in AP group increased compared with in control group one week after the operation, and markedly increased at 2 and 4 weeks after the operation(p<0.01)(serum PIP: 14.21±2.67 and 15.63±6.87, the expression of type I collagen: 416±16 and 438±17), while no expression of type I collagen in AP+MP group. Conclusion These results suggest that iliac artery balloon injury may induce increase of type I collagen synthesis,which can be inhibited by MP.