• Reduction of mean sitting diastolic blood pressure (MSDBP) [ Time Frame: from baseline to week 12 ] [ Designated as safety issue: No ]
• Decrease in MSSBP to < 95th percentile for age, gender and height [ Time Frame: at week 12 ] [ Designated as safety issue: No ]
• Change in mean ambulatory systolic blood pressure and mean ambulatory diastolic blood pressure over 24 hours in subset of patients [ Time Frame: week 12 compared to baseline ] [ Designated as safety issue: No ]
• Safety and tolerability of valsartan compared to enalapril [ Time Frame: every visit ] [ Designated as safety issue: Yes ]

• Reduction of mean sitting diastolic blood pressure (MSDBP) at Week 12 from baseline
• Decrease in MSSBP to < 95th percentile for age, gender and height at Week 12
• Change in mean ambulatory systolic blood pressure and mean ambulatory diastolic blood pressure over 24 hours in subset of patients, Week 12 compared to baseline
• Safety and tolerability of valsartan compared to enalapril

The purpose of this 12-week active controlled trial is to evaluate the safety and efficacy of valsartan 80/160/320 mg (weight stratified) compared with enalapril 10/20/40 mg (weight stratified) on sitting systolic blood pressure (SSBP) in 6 - 17 year old children with hypertension (SSBP ≥ 95th percentile for age gender and height).

• Drug: Valsartan
• Drug: Enalapril

Inclusion Criteria:

• Male or female, ages 6-17, with a documented history of hypertension
• Must be able to swallow a pill
• Must be ≥ 18 kg or ≤160 kg
• MSSBP (mean of 3 measurements) must be ≥ 95th percentile, for age, gender and height, at Visit 2 (randomization), by office blood pressure measurement
• Patients who are eligible and able to participate in the study and whose parent(s)/guardian(s) consent in writing (written informed consent) to their doing so after the purpose and nature of the investigation has been clearly explained to them. (An assent will be required for some patients depending upon their age and local requirements regarding assents)

Exclusion Criteria:

• Renal artery stenosis
• Current diagnosis of heart failure (NYHA Class II-IV).
• MSSBP ≥ 25% above the 95th percentile
• Second or third degree heart block without a pacemaker.
• Concurrent potentially life threatening arrhythmia or symptomatic arrhythmia.
• Clinically significant valvular heart disease.
• Patient that demonstrates clinically significant ECG abnormalities other than those associated with left ventricular hypertrophy.
• Previous solid organ transplantation except renal, liver or heart transplantation. Renal, liver or heart transplant must have occurred at least 6 months prior to enrollment. Patient must be on stable doses of immunosuppressive therapy for 3 months and deemed clinically stable by the investigator.

Other protocol-defined inclusion/exclusion criteria may apply