The purpose of this study is to compare depressor effect and safety between combination therapy with telmisartan plus low-dose hydrochlorothiazide and amlodipine in hypertensive patients.

In hypertensive patients whose blood pressure (BP) does not reach less than 140/90 mmHg with 5mg/day of amlodipine are divided the following two groups and BP response, laboratory data, and adverse effects are compared. Group 1: 12 week combination therapy with telmisartan plus low-dose hydrochlorothiazide. Group 2: Amlodipine is continuously administered.

Inclusion Criteria:

• 5 mg/day of amlodipine is administered for more than 3 months
• Systolic or diastolic blood pressure >= 140/90 mmHg (more than 2 times measurements at outpatient clinic before start of the study)
• Outpatients

Exclusion Criteria:

• Secondary hypertension including renovascular hypertension with single kidney or bilateral stenosis
• Administration of antihypertensives other than amlodipine
• Cardiovascular disease (cerebral hemorrhage, cerebral infarction, TIA, angina, myocardial infarction, acute renal failure) occurs less than 6 months before start of the study
• Serum creatinine >= 2.0 mg/dl
• Severe hypertension (systolic or diastolic blood pressure >= 180/110 mmHg) or malignant hypertension (hypertensive organ damage is rapidly developing)
• Chronic heart failure (NYHA class>=III to VI)
• Contraindication of telmisartan or hydrochlorothiazide
• Hyper- (>= 5.5 mEq/L) or hypo- (<=3.5 mEq/l) potassemia
• Untreated hyperuricemia or uncontrolled hyperuricemia (serum uric acid >= 8.0 mg/dl)
• Diabetic patients who require insulin therapy, uncontrolled diabetic patients (hemoglobin A1c >=9.0%), or patients who possess the risk of hypoglycemic attack
• Patients inadequate for the study