BIBR 277 Capsule in Patients With Essential Hypertension

Inclusion Criteria: * Patient is ≥ 25 years of age * Patient is either male or female * Outpatient. Change to inpatient is not allowed during the study period * Blood pressure is measured 3 times or more during the 4-week observation period; the last 2 measurements in the sitting position (intervals between measurements must be less than 4 weeks) are stabilized for both of systolic pressure (within +/- 30 mmHg) and diastolic pressure within +/- 15 mmHg) with the mean exceeding 160 mmHg for systolic and 95 mmHG for diastolic pressure Exclusion Criteria: * Patient has severe hypertension (the last 2 measurements in the observation period exceed 120 mmHg in terms of diastolic blood pressure) * Patient has secondary or malignant hypertension * Patient has a history of severe cardiac failure, unstable angina, or myocardial infarction within previous six months * Patient has atrioventricular conduction disturbance, atrial fibrillation or severe arrhythmia * Patient has any symptoms of cerebrovascular disorder * Patient has serious hepatic dysfunction (either GOT (glutamic-oxaloacetic transaminase) or GPT (glutamic-pyruvic transaminase) exceeds 100 U) * Patient has renal dysfunction (serum creatinin ≥ 2.1 mg/dl) * Patient has uncontrolled diabetic (either of the following tests exceeds the specified standards: fasting blood glucose exceeding 151 mg/dl or HbA1c exceeding 8%) * Patient has a history of drug sensitivity to ACE (angiotensin converting enzyme) inhibitors and angiotensin II receptor antagonists * Patient has a history of angioedema due to ACE inhibitors * Patient has hyperkalemia (K exceeding 5.5 mEq/l) * Patient has received enalapril just before the start of observation period * Patient has received treatment with any other investigational drug(s) within three months of the start of observation period * Patients is pregnant, breast-feeding, or possible pregnant, or wants to be pregnant during the study period * Patient has any other condition that the investigator or subinvestigator feels would be inappropriate for the study participation