IgA nephropathy is a common glomerulonephritis. About 30% of patients develop end-stage kidney disease within 20 years. A strategy for predicting prognosis from biopsy-based pathological evaluation has not been well established because of lack of reproducibility and inappropriate categorization. The new Oxford classification of IgA nephropathy provides a histopathological grading system with reproducibility for prediction of renal prognosis of IgA nephropathy independent of the clinical features. The classification must be validated in the different cohorts.