Abstract: To investigate the effect of long-term administration of marine collagen peptides on the life-span of SD rats, 160 SD rats of four weeks old were divided into the control group and MCP-treated groups, with 40 rats in each group (male:female=1:1). Control rats were fed with standard basal diets and the rats in the experimental groups were fed with 2.25%, 4.5% and 9% MCP in the control diet until their natural death. The bodyweight, food consumption and food efficiency were recorded throughout the experiment. The activity of serum antioxidant enzymes GSH-PX and SOD and the level of MDA were examined every six months. The results show that the MCP does not signifiantly influence body weight, food consumption or food efficiency of rats of either sex throughout the life span. The survival analysis shows that the median lifespan, the lifespan of the last 30% survivals and the maximal life span of MCP treated groups were notably longer than those in the control group. MCP did significantly inhibit the age-related decrease in the activities of antioxidant enzymes and the age-related increase in the levels of lipid peroxidation product in both sexes. When treated with MCP for 18 months and 24 months, the activities of serum GSH-PX and SOD enzymes of the 4.5% and 9% MCP treated rats were significantly higher than those of the control rats, whereas the serum level of MDA in the 4.5% and 9% MCP treated groups were significantly lower as compared with the control group. Therefore, the long-term administration of MCP could significantly extend the lifespan of SD rats, which might be attributed to the anti-oxidative property of marine collagen peptides.