The purpose of this study is to evaluate the safety and efficacy of three doses of valsartan (0.25, 1.0, and 4.0 mg/kg) on mean sitting systolic blood pressure (MSSBP) and mean sitting diastolic blood pressure (MSDBP) in 6 months - 5 year old children with hypertension (sitting systolic blood pressure [SSBP] ≥ 95th percentile ).

Inclusion Criteria:

• Children aged 6 months - 5 years at Visit 1, with a documented history of hypertension
• Must be able to swallow liquid formulation
• Must be ≥ 6 kg or ≤ 40 kg at randomization
• Must have documented history MSSBP (mean of 3 measurements) must be ≥ 95th percentile for age, gender and height, at randomization
• If patients enter with uncontrolled BP they can remain on background antihypertensives with an unchanged dosing regimen
• If patients have had a solid organ transplant more than 1 year ago they must be on stable doses of immunosuppressive therapy
• Parent(s)/guardian(s) are able to follow verbal and/or written instructions in the local language

Exclusion Criteria:

• Patients with background ARB therapy
• Patients demonstrating any clinically significant abnormalities or clinically noteworthy abnormal lab values (other than those relating to renal function)
• AST/SGOT or ALT/SGPT > 3 times the upper limit of the reference range
• Glomerular filtration rate < 30 mL/min/1.73m²
• Serum potassium > upper limit of the reference range
• MSSBP ≥ 25% above the 95th percentile
• Patients exhibiting clinically significant ECG abnormalities
• Patients that have coarctation of the aorta with a gradient of ≥ 30 mm Hg, or renal artery stenosis

Other protocol-defined inclusion/exclusion criteria may apply