 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. 