Introduction: Many of athletes look for supplementation of trace element in order to improve their performance. w e aimed to compare the effect of combined and separated supplementation of zinc and selenium on the serum level of Malondialdehyde, several hematological parameters, and also the performance of the road cyclists after exhausting exercise. Materials and methods: Thirty-two road cyclists from Tehran Traffic Cycling Team were assigned into four groups of zinc supplement (Zn), selenium supplement (Se), zinc-selenium supplement (Zn-Se), and placebo (P). In order to assess the basic values of the participants’ zinc, selenium, hematocrit (Hct), hemoglobin (Hb), and red blood cell count (RBC), blood samples were retrieved from each participant before supplementation. in addition, blood samples were collected before and after exhausting and their exhaustion time was recorded . After four weeks of supplementation, blood samples were collected again from the participants before and after performing exhausting exercise. Results: No significant difference was observed between groups in terms of exhausting exercise and supplementation on time to exhaustion and hematological parameters (P>0.05). Resting MDA level was lower in Zn-Se group compared to placebo (P˂0.05). Conclusion: four weeks of combined and separated supplementation of zinc and selenium did not lead to a significant change in the hematological parameters (Hb, Hct, and RBC) after exhausting exercise. It seems that when athletes do not show any deficiencies in Zinc and Selenium, supplementation will not be beneficial in order to improve their time to exhaustion.