A case of renal oncocytoma associated with focal segmental necrotizing glomerulonephritis is described. The patient showed haematuria, mild proteinuria and arterial hypertension; the diagnosis was made after right nephrectomy performed because of the presence of a renal mass. A severe re-activation of the glomerulonephritis was observed 15 months after the nephrectomy and a steroid and immunosuppressive therapy was started. Our case is the first reported in which the removal of renal oncocytoma is not followed by the disappearance of renal symptoms, as currently reported in literature, suggesting that the two diseases are not always related.