A 59-year-old female was referred to our department for a renal mass which was incidentally found during pneumonia treatment. Computed tomography and magnetic resonance imaging showed a 1.5-cm enhancing mass in the posterior midportion of the left kidney. Subsequently, an open partial nephrectomy was performed on the diagnosis of renal cell carcinoma. Pathological examinations revealed a hyaline-vascular type of Castleman's disease. Castleman's disease confined to the kidney is exceptionally rare. We present this rare case and review the literature concerning this unusual disorder.