Xanthogranulomatous pyelonephritis (XGPN) is a rare, severe, chronic renal infection typically resulting in a non-functioning enlarged kidney and is associated with obstructive uropathy secondary to nephrolithiasis. Delay in diagnosis and treatment may result in loss of a kidney and death. Here we report a patient who had a protruding mass over the left sided flank as the initial presentation of XGPN. She was managed successfully by percutaneous drainage followed by nephrectomy. The relevant issues regarding diagnosis and treatment of this disease are discussed.