The purpose of this study is to compare if the combination of valsartan 320 mg/lisinopril 20 mg versus the monotherapies of lisinopril 40 mg or valsartan 320 mg will result in a greater decrease of urinary albumin excretion measured as urinary albumin/creatinine ratio (UACR) in the first morning urine of hypertensive subjects with previously diagnosed microalbuminuria (MAU).

Inclusion Criteria:

• Patients with mild to moderate hypertension with a mean sitting diastolic blood pressure (MSDBP) > 85 and < 110 mmHg for non-treated patients. Previously treated patients with MSDBP < 110 mmHg. Treated is defined as having taken medication until < 2 days prior to Visit 1
• Positive urine spot test with Micral dipstick (detection of urinary albumin concentration of at least 50 mg/l) at Visit 1 (day -21).
• Confirmation of MAU of at least 2 out of 3 measurements determined in the first morning urine samples performed at Visit 1 day-21), Visit 2 (day -14) or Visit 3 (day -7). MAU is defined for male patients as urinary albumin creatinine ratio (UACR) > 2.5 mg/mmol and < 25.0 mg/mmol and for female patients as UACR > 3.5 mg/mmol and < 35.0 mg/mmol at both visits.

Exclusion Criteria:

• Evidence of renal impairment as determined by any one of the following:

  • serum creatinine clearance < 30 ml/min as determined by Cockroft and Gault formula [Cockroft and Gault, 1976] and/or
  • serum creatinine > 1.25 x ULN at Visit 1,
  • a history of dialysis, or
  • a history of nephrotic syndrome.

• Serum potassium values <3.5 mmol/l or >5.5 mmol/l at Visit 1

• Any medical condition which might significantly alter the urinary excretion of albumin

Other protocol-defined exclusion criteria may apply.