Idiopathic IgA nephropathy of Berger's disease is characterized by prominent and diffuse IgA deposits in the mesangium. In many countries, it is the most common type of primary chronic glomerulonephritis. Typically, it is revealed by recurrent episodes of gross hematuria in association with ENT infection, but it can progress insidiously with microscopic hematuria and proteinuria. Serum IgA levels are increased in about 50% of cases. IgA nephropathy is not a minor condition: 20% of patients develop end-stage chronic renal failure 10 years after diagnosis and 50% after 20 years. IgA nephropathy can recur in a transplanted kidney suggesting that this disease is a systemic disorder although it has a remarkable tropism for the kidney. Even though many points remain to be elucidated, its pathogenesis appears to be linked to a genetic factor responsible for a lymphocyte dysfunction and an acquired environmental factor such as penetration of an antigen via the mucosa which may give rise to an excessive and inappropriate IgA immune response with the deposition of IgA in the mesangium and the development of progressive renal alterations. No treatment has been shown to be effective but tonsillectomy advised in case of a recurrent tonsillar focal infection is most often accompanied by a decrease in the incidence of gross hematuria. Corticosteroid therapy can be of benefit in cases involving a nephrotic syndrome associated with minimal glomerular lesions. In all cases, control of possible hypertension is of value in slowing the progression of this disease.