Hyperphosphatemia is a common problem in end stage renal disease patients, and this patients need to use phosphorus binders. Calcium based phosphorus binders leads to calcium overload. Renagel and Lanthanum are expensive. Therefore a magnesium based phosphorus binder seems to be useful to be evaluated in these patients. The aim of this study was to evaluate the efficacy and safety of MgCo3 tablets in hyperphosphatemic end stage renal disease and compare its effects with CaCo3 tablets. Sample size was estimated 50 patients and selected from patients in Noor hospital dialysis center after getting a consent, with the inclusion criteria: 3 months on hemodialysis, P>5.5 mg/dl and age more than 18 years old. In case of irregular drug consumption or irregular hemodialysis, pregnancy, kidney transplantation, death, Ca × P > 54 in control group or Mg> 4 mg/dl the patient will be excluded. MgC03 tablets made in Amin pharmaceutical company. Patients were randomly divided in two groups to use either MgCo3 tablets 250 mg trice daily or CaCo3 500 mg trice daily with meal for six weeks. The patients will be examined in each dialysis session to find the possible complications. With the respect to laboratory findings in two weeks intervals the drug doses will be adjusted. Ca, P, Alb, Mg, VBG, CRP will be checked before trial and each two weeks until the end of the study. Triglyceride, Cholesterol, LDL, HDL, iPTH will be checked before trial and at the end of the 6th week. At the end the efficacy and safety of MgCo3 in hyperphosphatemia of these patients and serum Calcium, phosphorus, magnesium, iPTH, CRP, and lipid profile of two groups will be compared.