Background: Patients in the final stages of renal failure have accelerated inflammation conditions. Inflammation causes progressive kidney damage, faster progression of atherogenesis, chronic malnutrition and increased anemia, resulting in lower life expectancy of patients under dialysis. Statins have pleiotropic effects, because the drug has effects more than just decreasing lipids such as antioxidant effects, changes in endothelial dysfunction, stabilizing the plaque and immune system regulator. Objectives: The aim of the study was to evaluate anti-inflammatory effect of simvastatin (one of the statins) in patients under hemodialysis. Patients and Methods:In this clinical trial study, 40 patients under hemodialysis were studied for 12 weeks. Patients were divided into treatment (25 cases) and control groups (15 cases). The treatment group received a daily dosage of 20 mg of simvastatin, while the control group received no medication. The serum amounts of hs-CRP, IL6, Hb and WBC count were measured and compared at baseline and after 12 weeks. In addition, probable hepatic and muscular complications were studied in patients. Results: At baseline, each of treatment and control groups had similar characteristics. During the study, the average level of CRP decreased in the treatment group (P = 0.04), while it was increased in the control group. The amount of serum IL-6 dropped in the treatment group (P = 0.01); however, it was increased in the control group. In both groups, the level of Hb increased significantly at the end of study in the treatment group (P = 0.007) and the control group (P = 0.016). The average WBC count decreased significantly in the treatment group and the control group (P = 0.003). There was no significant change in hepatic and muscular enzymes in the two groups. Conclusions: End stage renal disease (ESRD) have accelerated inflammatory conditions. Simvastatin clearly lowers the serum levels of CRP and IL-6, and the white blood cell count in dialysis patients. Administering Simvastatin to dialysis patients is safe.