Emphysematous pyelonephritis (EPN) is a rapidly progressive, gas-forming and life-threatening infection of the renal, pelvicalyceal and perirenal tissues.Herein we report a 73-year-old female uremic patient with a renal mass associated with emphysematous pyelonephritis. Computerized tomography of the abdomen showed gas formation in the upper pole of the left kidney. After the failure of antimicrobial therapy and percutaneous
drainage, she was treated successfully with radical nephrectomy. The pathologic diagnosis of the left kidney showed existence of renal cell carcinoma in addition to EPN.