Efficacy and Safety of the Combination Aliskiren (300 mg) and Hydrochlorothiazide (25mg) to Aliskiren (300mg) Monotherapy in Patients With Staged II Hypertension

Inclusion Criteria: * Outpatients ≥18 years of age. * Patients with a diagnosis of Stage II hypertension, defined as mean sitting Systolic Blood Pressure (msSBP) ≥ 160 mmHg and \< 180 mmHg at Visit 2. Exclusion Criteria: * Severe hypertension defined as msSBP ≥ 180 mmHg and/or mean sitting Diastolic Blood Pressure (msDBP) ≥ 110 mmHg. * Secondary form of hypertension. * Current diagnosis of heart failure (New York Heart Association \[NYHA\] Class II-IV). * Current angina pectoris requiring pharmacological therapy (other than stable doses of oral or topical nitrates). * Second or third degree heart block without a pacemaker. * Concurrent potentially life threatening arrhythmia or symptomatic arrhythmia, atrial fibrillation or atrial flutter, during the 12 months prior to Visit 1. * Clinically significant valvular heart disease. * Previous history of hypertensive encephalopathy or stroke, Transcient Ischemic Attack (TIA), heart attack, coronary bypass surgery or any PCI. * Known Keith-Wagener grade III or IV hypertensive retinopathy. * In the month prior to Visit 1, patients on combination antihypertensive therapy that includes more than 2 classes of antihypertensive medications. * Patients on combined antihypertensive medication that contain two classes of antihypertensive medications are considered to take two antihypertensive medications. * Inability to discontinue prior antihypertensive or other CV medications as required by the protocol. * Patients with Type 1 diabetes mellitus. * Patients with Type 2 diabetes mellitus not well controlled . * Elevated Serum potassium (over 5.3 mEq/L (mmol/L). * Any surgical or medical condition or the use of any medication which might significantly alter the absorption, distribution, metabolism, or excretion of study drugs. Other protocol-defined inclusion/exclusion criteria may apply.