This is a dose ranging study of candesartan cilexetil in hypertensive pediatric subjects ages 1 to less than 6 years of age. It employs a double blind, randomized, dose ranging design intended for conduct as a multicenter trial. There are 3 study 'periods': a 1-week placebo run-in, a 4-week double blind treatment, and a 52-week open-label, long-term treatment period. Subjects undergo a screening evaluation, then a 1-week single-blind, placebo run-in, after which eligible subjects are allocated to receive 1 of 3 dose levels of candesartan cilexetil (0.05 mg/kg, or 0.20 mg /kg or 0.40 mg /kg), liquid formulation, in a 1:1:1 ratio for 4-weeks. At the end of randomized dose allocation (Day 28), blood pressure assessment will be performed and subjects may begin the 52-week, open-label treatment period of the study.

Inclusion Criteria:

• Signed informed consent by a parent or a legal guardian.
• Weight > 10 kg and < 40 kg.
• SiSBP and/or SiDBP > 95th percentile and < 20 mm Hg (systolic) and/or 10 mm Hg (diastolic) above the 95th percentile at screening and at randomization based on height-adjusted charts for age and gender.

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.
• Weight < 10 kg and > 40 kg.
• Less than 80% compliance with study medication during single-blind placebo screening as assessed by residual medication volume.
• Hypertension secondary to pheochromocytoma, hyperthyroidism, or Cushing's Syndrome.
• Uncorrected coarctation of the aorta, bilateral renal artery renal artery stenosis in a single kidney.
• Estimated glomerular filtration rate (GFR) < 50 mL/min/1.73m 2 based on the Schwartz Formula (Schwartz et al, 1987).
• Renal transplant < 6 months prior to study entry. Subjects who have received a renal transplant > 6 months prior to study entry may participate in the study if: 1) renal function is stable, 2) estimated GFR >50 mL/min/1.73m 2, 3) stable doses of immunosuppressive medications are anticipated throughout the 4-week, double-blind period of the study, 4) no episodes of acute allograft rejection have occurred within 30 days of study entry, and 5) the renal allograft has no documented renal artery stenosis.

Nephrotic syndrome not in remission.

• Unstable 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.
• 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 aspartate aminotransferase (AST) or alanine aminotransferase (ALT).
• Known hypersensitivity to ARBs.
• Currently receiving an angiotensin receptor blocker or an angiotensin converting enzyme inhibitor that in the investigator's judgment cannot safely be withdrawn during the study.
• Subjects receiving an angiotensin receptor blocker or an angiotensin converting enzyme inhibitor may be eligible if they undergo withdrawal of the antihypertensive medication over a 2-week washout period and subsequently meet BP inclusion/exclusion criteria.
• Subjects currently receiving other classes of antihypertensive medications (eg, diuretics, calcium channel blockers or beta-blockers) and whose BP values meet inclusion/exclusion criteria may participate in the study while continuing their current antihypertensive medication regimen. Up to 2 concomitant antihypertensive medications are permitted. Doses and dose regimens of concomitant antihypertensive medications must remain unchanged during the 4-week double-blind period of the study.
• 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 suspension.