Castleman's disease is a rare lymphoproliferative disease and its etiology is still unknown. It may occur at every site where lymph tissue is present. A definitive treatment is possible with complete resection. The most important problem is bleeding which may occur during surgery due to the high vascularization. In this study, we present the surgical treatment of a case with mediastinal Castleman's disease, treated preoperatively with embolization because of hypervascularization detected on thoracic CT.