The aim of this trial is to determine the best dose combination of S-Amlodipine and Telmisartan as compared to monotherapy by assessing the blood pressure lowering effects of a once daily regimen of various combinations of S-Amlodipine and Telmisartan, compared to their monotherapy components and placebo, in patients with stage I or II essential hypertension(a mean seated cuff diastolic blood pressure >=95 and <=115 mmHg).

Inclusion Criteria:

• age 18 years or older
• stage I or II hypertension defined as: a mean seated cuff diastolic blood pressure >=95 and <=115 mmHg
• ability to provide written informed consent

Exclusion Criteria:

• severe hypertension defined as: a mean seated cuff diastolic blood pressure >=116mmHg or a mean seated cuff systolic blood pressure >=200mmHg
• known or suspected secondary hypertension(ex. aortic coarctation, Primary hyperaldosteronism, renal artery stenosis, pheochromocytoma)
• has severe heart disease(Heart failure NYHA functional class 3, 4), unstable angina or myocardial infarction, arrhythmia within the past three months
• has cerebrovascular disease as cerebral infarction, cerebral hemorrhage within 6 months
• Type I Diabets Mellitus, Type II Diabetes Mellitus with poor glucose control as defined by fasting glucosylated hemoglobin(HbA1c) > 8%
• known severe or malignant retinopathy
• hepatic or renal dysfunction as defined by the following laboratory parameters: AST/ALT > UNL X 2, serum creatinine > UNL X 1.5
• acute or chronic inflammatory status need to treatment
• need to additional antihypertensive drugs during the study
• need to concomitant medications known to affect blood pressure during the study
• history of angioedema related to ACE inhibitors or Angiotensin II Receptor Blockers
• known hypersensitivity related to either study drug
• history of drug or alcohol dependency
• any surgical or medical condition which might significantly alter the absorption, distribution, metabolism, or excretion of investigational products(ex. gastrointestinal tract surgery such as gastrectomy, gastroenterostomy or bypass, active inflammatory bowel syndrome within 12 months prior to screening, currently active gatritis, ulcers of gastrointetinal/rectal bleeding, impaired pancreatic fuction such as pancreatitis,obstructions of the urinary tract or difficulty in voiding)
• cannot swallow investigational products
• administration of other study drugs within 4 weeks prior to randomization
• premenopausal women(last menstration < 1year) not using adequte contraception, pregnant or breast-feeding
• history of malignancy including leukemia and lymphoma within the past 5 years
• in investigator's judgment