Inclusion Criteria:

• The subjects must have fulfilled the eligibility criteria for and have participated in Study 261A or did not participate in Study 261A but meet the following criteria:
• Diagnosed and untreated hypertension, or
• Diagnosed and treated, but off antihypertensive treatment for at least 2 days with a mean sitting systolic blood pressure and/or sitting diastolic blood pressure ≥ 95th percentile and ≤ 20 mm Hg (systolic) and/or 10 (diastolic) mm Hg above the 95th percentile based on height-adjusted charts for age and gender.
• Females of childbearing potential (post-menarche), must have a negative urine pregnancy test and adhere to a pregnancy prevention method (abstinence, a barrier method plus a spermicidal foam or an oral or implanted contraceptive).
• A signed informed consent by a parent or a legal guardian and an assent form signed by the subject (if applicable).

Exclusion Criteria:

• Any situation, clinical condition or laboratory abnormality that, in the opinion of the investigator or sponsor, may interfere with the subject's participation in the study or would pose a significant risk to the subject or interfere with the assessment of safety and efficacy endpoints.
• Hypertension secondary to coarctation of the aorta, pheochromocytoma, hyperthyroidism, Cushing's syndrome, or medications (eg: corticosteroids).
• Known history of bilateral renal artery stenosis, unilateral renal artery stenosis or a renal transplant.
• Glomerular filtration rate < 50 mL/min based on an estimated value using the Schwartz Formula.
• Nephrotic syndrome not in remission.
• Insulin dependent diabetes mellitus.
• Known bleeding, coagulation, or platelet disorder that could interfere with blood sampling.
• Clinically significant valvular heart disease.
• Clinical diagnosis of heart failure.
• Clinically significant arrhythmia (eg, any arrhythmia requiring medical therapy or that causes symptoms).
• Second or third degree AV block.
• Pregnant or breast-feeding an infant.
• Impaired liver function defined as either acute liver disease or chronic liver disease with persistent liver enzyme values greater than 1½ times the upper limit of the reference range for AST or ALT.
• Known hypersensitivity to ARBs.
• Unable to be off antihypertensive medication (diuretics, beta blockers, ACE Inhibitors, etc) for 6-weeks.
• Inability to discontinue medications which may contribute to elevated blood pressure e.g. systemic corticosteroids.
• Currently using, or used within 14 days prior to receiving double-blind medication, any concomitant medications which in the opinion of the investigator could negatively affect the subject.
• Unable or unwilling to comply with the study requirements including blood sampling and swallowing study drug tablets.
• Received an investigational agent within 30 days prior to receiving study medication (except in Study 261A).
• Alcohol or drug abuse.