Despite clear evidence that blood pressure lowering treatment is beneficial for reduction of cardiovascular disease, blood pressure levels are not adequately controlled in many hypertensive patients. More intensive blood pressure lowering treatment is required to achieve maximum reduction of cardiovascular disease. Combination pills of blood pressure lowering drugs could be a safe and effective strategy to achieve blood pressure target but there is no randomized evidence that established the beneficial effects of combination pills of blood pressure lowering drugs. The purpose of the study is to determine whether combination pill of losartan potassium and hydrochlorothiazide will improve medication compliance among patients with high blood pressure.