Objective To evaluate the clinical value and efficacy of transcatheter preoperative superselective arterial embolization in sacral or ilium tumors.Methods The procedures of superselective arterial embolization with gelfoam were performed in 15 cases. The lesions included giant cell tumor of bone (n = 5) , aneurysmal bone cyst (n = 2) ,chordoma (n = 2) , metastatic tumor (n = 4)and chondrosarcoma (n = 3) . The operations of resection were done 1 to 5 days after superselective arterial embolization.Results Angiograms showed marked reduction (80% or more) of the tumor's staining after embolization. In this series ,the average blood loss was 1100 ml ,during operations(aranged from 500 ml to 2600 ml),and all tumors were completely resected.Conclusion Preoperative transcatheter selective arterial embolization is an effective and safe method in reducing blood loss during operations and improving therapeutic effect for sacroiliac tumors.