【Abstract】Objective To research relation of apoptosis muscular cell in 103Pd radioactive stent of dog biliary muscular formation and inhibition of biliary ductal stricture. Methods Twelve dogs were randomly divided into two groups, which were general stent group and 103Pd radioactive stent group. General stent and 103Pd radioactive stent were respectively put into extrahepatic biliary tract of two groups. After 30 days all dogs were killed, and biliary tract were taken out. Apoptotic cells were detected by immunohistochemical methodsand agar electrophoresis, and nucleus browyellow was positive cell. Dog biliary duct cross-sections were stained by hematoxylin-erosin; area and perimeter of lumen,thickness of inner membrane and stenosis degree in bile duct were analysed by image analysis software of computer.Results The apoptotic biliary duct smooth muscle cell ［(87.9±7.96)/cm2］ was more significantly increased in the 103Pd radioactive stent group than in the general stent group ［(5.6±0.51)/cm2］, P＜0.05; and comparing with the general stent group, the 103Pd radioactive stent significantly reduced biliary muscular formation thickness. Conclusion The result shows that 103Pd radioactive stent can inhibit proliferation of biliary ductal smooth muscle cell.