In the present study, we measured serum and urinary levels of NGAL, MMP-9 and MMP-9/NGAL complex in patients with oncocytoma and clear cell renal cell carcinoma (ccRCC) in order to verify whether these molecules may offer a potential non-invasive biomarker to provide useful clinical information for kidney carcinoma. This evidence concerns the gene MMP9 and clear cell renal carcinoma.