Evaluate the diastolic blood pressure lowering effect of combination of aliskiren 300 mg and HCTZ (12.5 mg and 25 mg) in hypertensive patients who do not show sufficient blood pressure response to aliskiren 300 mg.

Inclusion Criteria:

• Male or female outpatients 18 years old or older.
• Patients with a diagnosis of hypertension.
• Patients who are eligible and consent to participate in the study

Exclusion Criteria:

• Severe hypertension
• Previous or current diagnosis of heart failure.
• History of hypertensive encephalopathy or cerebrovascular accident, transient ischemic cerebral attack (TIA), myocardial infarction, coronary bypass surgery, or any percutaneous coronary intervention (PCI).
• Other protocol-defined inclusion/exclusion criteria may apply