Because primary renal-cell carci-noma is relatively unresponsive to chemotherapy or radiotherapy, the resection or ablation of early-stage disease is the only option with a possibility of cure [1], However, most small renal masses are now de-tected incidentally during ultra-sound, computed tomographic, or magnetic resonance imaging (MRI) examinations for nonuro-logic indications, in patients with no clinical signs of renal-cell carci-noma, such as persistent micro-scopic hematuria [2]. A substantial proportion of these smaller masses are benign (Table 1) [3]. Ultrasound, computed tomo-graphic, and MRI techniques can definitively characterize some be-nign lesions, such as fat-containing angiomyolipomas and simple renal cysts. Otherwise, all non-fat-con-taining lesions that enhance after the administration of intravenous contrast agents are considered sus-pect for cancer [2,4]. Until re-cently, percutaneous biopsy was not considered accurate enough for diagnosis. Therefore, masses that were not definitively benign on im-aging were routinely resected or ab-lated without confirmed diagnoses of malignancy because of the high likelihood of renal-cell carcinoma. Recent advances in radiologic and pathologic techniques have in-creased the accuracy of image-guided percutaneous biopsy, and its use has been shown to decrease the likelihood of finding a benign lesion on nephrectomy [5]. There-fore, percutaneous biopsy plays a role in the diagnosis and manage-ment of small renal masses and can spare unnecessary and potentially morbid surgical procedures.