Angiosarcoma, a rare aggressive malignant tumor thought to be of vascular origin with high potential for metastasis, frequently occurs on the scalp of elderly people. Recent findings have shown that overexpression of basic fibroblast growth factor and its receptor is associated with neoplasia, which suggests that basic fibroblast growth factor promotes tumor vascularization and subsequent growth. In this study, we examined the immunohistologic localization of basic fibroblast growth factor and its receptor in angiosarcoma. Our results suggest that basic fibroblast growth factor synthesized in the tumor endothelial cells plays an important role in the growth and progression in angiosarcoma and that serum basic fibroblast growth factor levels are elevated in patients with nodular type angiosarcoma. (J Am Acad Dermatol 1999;41:127-9.)