Radionuclide bone scans were obtained as part of the routine evaluation of 85 patients with renal cell carcinoma. Twenty-nine patients (34%) were found to have metastatic disease at presentation. Bone scans were abnormal in 27 of these 29 patients for a sensitivity of 93 per cent; of the remaining 56 without metastatic disease, 48 had normal bone scans for a specificity of 86 per cent. In all patients whose abnormal bone scans indicated metastatic disease, there were either clinical signs (bone pain), laboratory findings (elevated alkaline phosphatase), or routine radiographic procedures (chest roentgenogram, intravenous pyelogram, or angiogram) suggesting disease metastatic to bone. Although bone scanning was useful for confirming clinically or radiographically suspected metastatic disease, it did not influence the staging of the renal cell carcinoma in any patient. We therefore conclude that bone scans should be used to confirm the presence and to determine the extent of osseous metastases in patients with renal cell carcinoma but are unnecessary as a routine staging procedure.