The study will be a prospective non randomized trial. All patients fulfilling the inclusion and exclusion criteria will be treated with losartan 50 mg once daily for one month. After a wash out period of one week losartan treatment will be replaced with valsartan 160 mg once daily. Patients will be evaluated at baseline and following losartan and valsartan treatment. Patients will undergo a 24 hour ambulatory BP monitoring at baseline, one months following losartan treatment and one month following valsartan treatment. Creatinine and Potassium levels will be measeured at baseline and one week following each drug administration, blood sample will be collected to measure the losartan/ E-3174 ration.