An accurate preoperative diagnosis of xanthogranulomatous pyelonephritis is difficult because of its clinical and radiological similarities to renal cell carcinoma. We report two cases of xanthogranulomatous pyelonephritis. Furthermore, in an attempt to clarify the clinical distinction between this entity and renal cell carcinoma, we summarize the clinical characteristics of 143 cases with xanthogranulomatous pyelonephritis in the literature and 126 cases with renal cell carcinoma experienced in our clinic. According to the clinical reviews, several characteristics of xanthogranulomatous pyelonephritis were revealed. 1) Presence of history of pyelonephritis. 2) gamma-globulinemia in blood chemistry. 3) Non-visualizing kidney on the excretory urogram. 4) Hypovascular or avascular features and dilatation of renal capsular arteries on angiogram. 5) Heterogenous renal mass and thickness of Gerota's fascia on computed tomogram. 6) Positive uptake of renal mass in Ga-scintigram. When some of these features are found in the renal mass, the case could be of xanthogranulomatous pyelonephritis and therefore a kidney preserving operation should be considered.