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.

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.

Inclusion Criteria:

• Aged 20 years or above
• Hypertension defined as blood pressure levels of >/=140/90mmHg or current use of blood pressure lowering drugs
• Able to commence combination therapy of angiotensin receptor antagonists and diuretics

Exclusion Criteria:

• Blood pressure measurements of >/=200/120mmHg
• Previous serious adverse events due to angiotensin receptor antagonists or diuretics
• Known or possible pregnancy
• Known severe liver dysfunction
• Known severe kidney disease
• Known contraindication to angiotensin receptor antagonists or diuretics
• Taking >/=4 tablets except for angiotensin receptor antagonists
• ACE inhibitors, thiazide or thiazide-like diuretics in the morning
• Current participation in another clinical trial
• A high likelihood that the patient is not suitable for the study treatment