Currently, IgAN treatment recommendations are only based on clinico-biological parameters. Steroids therapy appears to have a major role in IgAN treatment, but previous studies evaluating steroids lacked of optimal control group and reproducible evaluation criteria. No prospective study with optimal RAS blockade had included renal pathology in patients selection criteria, although histological evaluation improves patients prognosis prediction. Until now, the lack of a reliable histological classification has precluded the use of histological lesions to evaluate IgAN prognosis and treatment. Given the recently identified major prognostic role of histological lesions in IgAN, we propose to introduce renal pathology to guide the treatment of IgAN in a multicenter study, using currently validated evaluation criteria of chronic kidney disease progression.