This study will assess the efficacy and safety of valsartan/hydrochlorothiazide combination therapy in patients with hypertension not controlled with hydrochlorothiazide monotherapy.

Inclusion Criteria:

• Male or female 18 years of age and older
• Diagnosed as having hypertension (mean seated systolic blood pressure ≥ 150 mm Hg but < 180 mm Hg and mean seated diastolic blood pressure ≥ 95 mm Hg and <110 mm Hg

Exclusion Criteria:

• - Patients with sever hypertension: Systolic ≥ 180 mm Hg or Diastolic ≥ 110 mm Hg
• Diabetes with fasting glucose > 126 mg/dl or on existing anti-diabetic medication
• History of stroke, transient ischemic attack, or myocardial infarction within the last 6 months, or diagnosed with congestive heart failure.

Other protocol-defined inclusion/exclusion criteria may apply.