Primary IgA mesangial nephropathy was first described in adults by Berger, and has been increasingly recognized in children. IgA nephropathy is a frequent type of glomerulonephritis in 3 to 15 year-old children in France. Clinical features and outcome have been defined and the progression to renal failure is possible. The pathogeny of IgA nephropathy remains unclear and is under multifactorial control and, at present, no satisfactory specific treatment is available.