Background and Objectives: A great amount of evidence shows that Oxidative stress is high among hemodialysis patients. The purpose of present investigation is examination of the effect of zinc supplementation on improvement of oxidative stress in chronic hemodialysis patients.

  Methods: In this double blind clinical trial 65 chronic hemodialysis patients were studied in two groups Group one (35 patients) received placebo and group two (30 patients) received 100 mg elemental zinc (as zinc sulfate) daily for 2 months. The placebo and supplement discontinued in next 2 months. Then, the study continued for two other months in the cross-over from. The levels of serum zinc, total glutathione, malondialdehyde (MDA), total serum antioxidant capacity and the activity of whole blood superoxide dismutase (SOD) were determined on 0^th, 60^th,120^th,180^th days, in fasting, predialysis samples. Food record was recorded for one day prior to dialysis in above-mentioned days and their dietary zinc was assessed.

  Results: Basal serum zinc levels in both groups were below 80 μ g/dl. The zinc upplementation led to significant increase in the levels of serum zinc in both groups .The levels of serum total antioxidant capacity, total glutathione and activity of whole blood SOD increased significantly during zinc supplementation period. The concentrations of serum MDA decreased significantly in zinc supplementation period in both groups. During the placebo period the levels of MDA in first group increased significantly, whereas the concentration of glutathione in second group decreased significantly. The body mass index (BMI) values did not change significantly during the study.

  Conclusion: It can be concluded that in patients undergoing hemodialysis the oxidative stress enhanced during nonsupplementation period (zinc sulfate). Low serum zinc levels are improved by zinc administration and zinc supplementation improves oxidative stress.