Abstarct: Background and Objectives: Some athletes and coaches believe that, do the exercise with more intensity, their ability to obtain record to is higher. The pressures of training, physical problems such as illness, fatigue, muscles aches and produce large amounts of free radicals, (ROS) that can cause cell damage in athletes. Hence, strengthening the body's antioxidant system, thereby reducing the harmful effects of free radicals to.The aim of this study was to investigate the effect of silymarin supplementation and endurance training on MDA, LDH and CK in sedentary men (age: 25±5 years, weight 86±21, height 178±13, BMI 27±5, N= 22) Student of Shahrood University That The 91-92 school year has been a physical education course. Materials and Methods: The research was semi-experimental and subjects randomly divided to supplemental groups (n = 11) and placebo groups (n = 11). Then both groups for 6 weeks, while consumed silymarin supplements (Day 2 tablets of 140 mg) or placebo (2 capsules a day ) endurance training began. Blood samples collected before and after 6 weeks exercise training and supplementation intake. Blood sample was before and after training and supplementation to measurements of lipid peroxidation (MDA), Lactate dehydrogenase (LDH) and Creatine kinase (CK). Data was analyzed with SPSS16 analysis software repeated measure (2×3). Results: A significant reductionin MDA in supplement groups was observed after 6 weeks of endurance training (P = 0.012). Despite this non-significant increase in the enzyme lactate dehydrogenase (P = 0.101) and creatine kinase (P = 0.626) was observed. Conclusions: The results of this study showed that endurance training with in silymarin supplementation cause significant reductionin lipid peroxidation. It seems that the type and intensity of exercise and the dose of silymarin supplementation intake could be very important factors MDA index in sedentary men