Immunoglobulin (Ig) A nephropathy is one of the most common causes of glomerulonephritis worldwide. Its prognosis can be totally different in various patient populations, ranging from asymptomatic slow progression to end-stage renal disease in as much as 40% of patients in few months to years. This disease process can be idiopathic, or it can be associated with a variety of disease processes. Various risk stratification scoring systems are available, which can predict the long-term outcome. New evidences are also emerging that IgA nephropathy is an autoimmune disease with a known antigen, galactose-deficient IgA1, which can elicit an autoantibody response and formation of immune complexes that are deposited in the mesangium.