The purpose of this study was to correlate the effectiveness of preoperative embolization with the blood loss and transfusion requirement during surgery for bone metastases from renal cell carcinoma. Twenty-eight preoperative embolizations in 26 patients with renal cell carcinoma metastatic to bone were retrospectively evaluated and divided into two groups: Group A included the embolizations that resulted in complete devascularization of the lesion as defined by the post-embolization arteriograms, and group B included those with an incomplete result. The two groups were compared with regard to blood loss and transfusion requirement during surgery, by unpaired two-tailed Student's t-test. Where complete embolization was effected (group A, 10 cases), there was a mean blood loss of 535 +/- 390 ml. When a less than complete embolization was achieved (group B, 18 cases), the mean blood loss was 1.247 +/- 1.047 ml (p = 0.049). The red blood cell transfusion in group A was 1.3 +/- 1 units, whereas in group B it was 2.4 +/- 1.2 (p = 0.03). Preoperative embolization of bone metastases from renal cell carcinoma with subsequent complete devascularization leads to significant reduction of blood loss during surgery. Interventional radiologists should pursue and embolize every feeder to the metastasis, because any less than complete devascularization increases the amount of blood loss and the amount of red blood cell transfusion during surgery.