Immunoglobulin A (IgA) nephropathy is the most common type of primary glomerulonephritis in the world. Current treatment with angiotensin converting enzyme (ACE) inhibitor and angiotensin receptor blocker (ARB) is not entirely effective. Aliskiren, a direct renin inhibitor, acts on the rate limiting step of the renin-angiotensin axis. In addition to lowering the blood pressure, recent study in diabetic nephropathy suggests an independent anti-proteinuric effect. The investigators plan to conduct a randomized placebo-control cross-over study to evaluate the safety and efficacy of aliskiren in the treatment of IgA nephropathy. The investigators plan to recruit 57 patients with biopsy-proven IgA nephropathy and persistent proteinuria despite conventional therapy. They will be randomized to aliskiren for 16 weeks or no treatment, followed by cross over to the other arm after a washout period. Proteinuria, albuminuria, renal function, serum and urinary markers will be quantified. This study will explore the potential anti-proteinuric effect of aliskiren in the treatment of IgA nephropathy, which has no specific treatment at present.

Inclusion Criteria:

• aged 18-65 years
• requires anti-hypertensive therapy
• renal biopsy within the past 3 years and confirmed the diagnosis of IgA nephropathy
• proteinuria > 1 g/day (or proteinuria > 1 g/g-Cr) in 3 consecutive samples within 12 weeks despite ACE inhibitor or ARB treatment for at least 3 months
• estimated glomerular filtration rate > 30 ml/min/1.73m2
• willingness to give written consent and comply with the study protocol

Exclusion Criteria:

• Patients who are diabetic, and patients with systemic diseases that may cause IgA nephropathy or another nephropathy.
• Pregnancy, lactating or childbearing potential without effective method of birth control
• Severe gastrointestinal disorders that interfere with their ability to receive or absorb oral medication
• History of malignancy, including leukemia and lymphoma within the past 2 years
• Systemic infection requiring therapy at study entry
• Any other severe coexisting disease such as, but not limited to, chronic liver disease, myocardial infarction, cerebrovascular accident, malignant hypertension
• History of drug or alcohol abuse within past 2 years
• Participation in any previous trial on aliskiren or other renin inhibitor
• Previous treatment with fish oil, steroid, cytotoxic agents, or aldosterone antagonist
• History of treatment with other drugs that may affect proteinuria within past 2 years
• Patients receiving treatment of corticosteroid
• On other investigational drugs within last 30 days
• History of a psychological illness or condition such as to interfere with the patient's ability to understand the requirement of the study
• History of non-compliance
• Known history of sensitivity or allergy to aliskiren or other renin inhibitor