For this reason، 14 student 11-14 years-old selected randomly from voluntary subjects. In thePreliminary session VO2max (39/9±4/9)، weight (46/07±5/33)، height (1/55±0/08)، fat percent(16/7±5/6)، body composition، BMI (18/9±1/5)، skeletal age (12/4±0/9) with X-ray، pubertalage with Tanner-stage (T3،T4) was measured and determined familiar illness was done fourday before experimental session .In experimental session ، firstly، pre-exercise blood samplecollected in fasted state، then every subject on ergometer cycle starts cycling with 65-70%VO2max for 40 min، post 10 min warming. Immediately post-exercise and recovery bloodsample drawn for measurement of plasma leukocyte ، C-reaction protein and IL-6. Dataanalyzed using The analysis of variance with repeated measures (R-ANOVA) test. The resultshowed there was a significant relation between different blood sampling.Results: The post hoc (LSD) test also used to find significant differences between each pair ofphases shown lymphocyte، monocytes، neutrophils counts and IL-6 level Immediately postexercise(p value respectively was 0.01، 0.027، 0.02، 0.001) also neutrophils، eosinophils countand IL-6 and hs-CRP levels one hour after exercise statistically was more than pre-exercise (pvalue respectively was 0.01، 0.04، 0.03، 0.00).Conclusion: the results of this study have shown، the exercise with mean intensity increase levelof some immune and inflammatory factors in immature boys.