The purpose of this study was to evaluate the effect of moderate physical exercise program on a number of immune parameters in middle school boys($15.07{pm}0.39$ yrs). 14 volunteers were included in this physical exercise program. They were randomly assigned to an experiment(7) and a control(7) group. Measurements were taken before program, after 4 weeks and 8 weeks of aerobic exercise for immune parameters such as number of circulating leukocytes, concentration of WEC subsets, lymphocyte subsets, immunoglobulins, complements, and number of blood adipose components. Aerobic exercise consisted of track running at a work intensity of 65% HRmax, $45{sim}55$ min per day, 3 times per week, and for 8 weeks. The results are as follows; 1. There were no significant changes between and within groups in the number of circulating leukocytes and concentration of WEC subsets. 2. There were significant(p<.05) changes in concentration of B-cell between groups, and T-cell, helper T-cell, and B-cell within experimental group. 3. There were no significant changes between and within groups in concentration of complements. 4. There were significant(p<.05) changes in concentration of IgG between groups and within experimental group. 5. There were significant(p<.05) changes in concentration of TG between groups, and TG, HDL-C and LDL-C within experimental group. In conclusion, the moderate exercise training for 8 weeks can be beneficial on immune function and decrease the concentration of flood adipose components in adolescents.