This randomized controlled clinical trial study was designed to investigate efficacy of losartan in treatment of post renal transplantation hyperuricemi. After signing informed consent, total 70 kidney transplanted patient with normal and stable renal function enter into our study.Exclusion criteria are: 1- renal artery stenosis 2- episode of acute rejection during last month 3- cardiac and cerebrovascular complications during last month or every abnormal function of heart, lung or liver 4- receiving ARBs, ACEIs or uric acid lowering agents and during study: 5- more than 50% rise in serum creatinine 6- SBP<90mmhg orDBP<60mmhg 7- hemoglobin below 100 g/ L. They are cathegorized into two groups , 35 patients recieving losartan and 35 patients with no drug reception as control. Patients group take 50 mg per day losartan for 6 months. Serum potassium concentration, serum albumin, urea nitrogen level, serum creatinine, serum uric acid, hemoglobin and whole blood CsA through level willbe measured 1,2,3 and 6 months therafter.All the patients willbe on 3 drug protocol including a Calcineurin inhibitor, Steroid, Cellcept or Imuran. Patient's blood pressure and GFR willbe measured frequently.No one takes ACEIs, ARBs or uric acid lowering agents before enterance into the study. Indications for prescription of losartan are: hyperuricemia (uric acid>7mg/dl) and abscence of above contraindications.