The purpose of this study is to evaluate the blood pressure lowering effects of an amlodipine/losartan combination treatment and amlodipine monotherapy for treatment of Stage 2 hypertensive patients.

Inclusion Criteria:

• 18 aged or over
• Patients with blood pressure measured at Visit 1; MSSBP≤180mmHg and MSDBP≤110 mmHg if on anti-hypertensive drugs, 160mmHg≤MSSBP≤199mmHg and 80mmHg≤MSDBP≤119mmHg if not on anti-hypertensive drugs
• Patients with blood pressure measured at Visit 2 were 160mmHg≤MSSBP≤199mmHg and 80mmHg≤MSDBP≤119mmHg

Exclusion Criteria:

• Inability to stop all prior anti-hypertensive drugs safely during wash out period of 3 to 7 days
• ≥ sitSBP 20mmHg or ≥ sitDBP 10mmHg of variation in three measurements from the reference arm selected at Screening
• History of hypersensitivity to dihydropyridines, angiotensin II receptor blockers or thiazide diuretics
• Secondary hypertension or suspected to be
• Continuously took medicinal drugs that might affect blood pressure rather than anti-hypertensive drugs more than 3 months
• Type 2 diabetes mellitus which is not controlled or with type 1 diabetes mellitus
• History of severe neurovascular disease, severe heart disease
• Known as moderate or malignant retinopathy.
• Renal diseases; serum creatinine ≥ 2mg/dl
• Hepatic diseases; increase in ALT or AST ≥ 2xUNL
• Anuria
• Hyponatremia/hypokalemia or hypercalcemia
• Active Gout
• Surgical or medical diseases which might significantly change ADME of medicines
• History of malignant tumor
• Autoimmune diseases
• History of alcohol or drug abuse
• Positive to pregnancy test, nursing mother, woman with an intention of pregnancy
• Considered inappropriate to participate in the clinical trial with any reason, based on investigator's decision

Other protocol-defined inclusion/exclusion criteria may apply