Abstract: this research was done to determine the effect of using L-carnitine and selected exercises on aerobic capacity and blood lactate. In this study 30 unathletes students of Shahid Rajaee University took part with the age of 22/63±1/75, height: 176 cm, weight 71/33±1 and BMI: 23/17±2/6. Subjects randomly divided into 3 groups, control group who were doing the selected exercises, experimental group 1 who received L-_carnitine and experimental group 2 who received L-carnitine and were doing the selected exercises. Exercises contain 4 weeks, 3 sessions of 60 minutes interval 65-85 percent oxygen uptake. Before and after 4 weeks the aerobic capacity was measured by Bruce test and blood lactate by loctometers. Data was evaluated by using descriptive statical methods and kolmogrof smirnoof and Levin test and dependent Test and one way ANOVA. Exercise, supplement, and exercise with¬¬ supplement had meaningful effect on the aerobic capacity and rest blood lactate (p?/005) and donot meaningful effect on the maximal blood lactate. there were not such a significant difference between exercise, supplement and exercise with supplement on the aerobic capacity,rest blood lactate and maximal blood lactate. So to improve the function sports and deacrase aerobic power we can use the L-carnitine supplement with the exercise.