Introduction. None of the classification systems in immunoglobulin A (IgA) nephropathy has been widely agreed or implemented by clinicians or pathologists. In order to meet this need, "Oxford Classification System", which is highly reproducible and predictive for clinical course, was developed in 2009. In the present study, we investigated clinical and pathological characteristics of patients with IgA nephropathy based on current classification and the predictivity of crescent presence on prognosis. Methods. The study comprised 40 patients with diagnosis of primary IgA nephropathy on renal biopsy. The biopsy findings and follow-up parameters of patients were retrospectively re-evaluated. Pathological findings were examined based on the Oxford classification system. The presence of crescent formation in the specimens was noted. Results. The presence of crescent formation was predictive of poor prognosis regarding the glomerular filtration rate (eGFR), the level of proteinuria, and mean arterial pressure (MAP). Conclusion: Considering the importance of crescent formation in prediction of the clinical course and need for immunosuppressive therapy, it is suggested that crescent presence can be included in this classification system.