Cases filed as vascular tumor of bone other than ordinary hemangioma were reviewed. They were included in the study if there was adequate histologic material and clinical information, clear evidence of bone origin, and at least 5 years follow-up. The study group comprised 17 cases, of which 13 were categorized as hemangioendothelioma of bone, 1 as epithelioid hemangioendothelioma, and 3 as high-grade angiosarcoma. Hemangioendothelioma of bone had growth patterns varying from vasoformative to solid, but well-formed vessels were present in at least some area in all cases. The cells generally had a rounded, epithelioid character, regular nuclei, and relatively few mitotic figures; occasional features included spindle cells and scattered enlarged, hyperchromatic or pleomorphic nuclei. Lymphoplasmacytic and eosinophilic inflammatory infiltrate ranged from prominent to slight or absent, and myxoid or hyaline stroma was never more than focal. Epithelioid hemangioma could not be separated from hemangioendothelioma of bone. The single epithelioid hemangioendothelioma for the most part had cords of relatively uniform epithelioid cells in a prominent myxoid stroma but focally demonstrated an angiosarcoma-like appearance, with irregular vascular spaces and marked nuclear pleomorphism. The high-grade angiosarcomas exhibited predominantly irregular vasoformation combined with solid areas, diffuse nuclear hyperchromatism and pleomorphism, and, in 2 cases, numerous mitotic figures (the third case had only a small biopsy and a postradiation amputation specimen). Of the hemangioendotheliomas of bone, 7 were unicentric and 6 were regionally multicentric either concurrently or sequentially. Three patients had intraosseous local recurrence, 2 had discontinuous regional skin or soft tissue involvement (including the popliteal artery in 1), and 1 had a solitary lung metastasis, but none died of tumor. The patient with epithelioid hemangioendothelioma had multicentric tumors in widely separated bones and died with liver and lung metastases. Two of the high-grade angiosarcomas were unicentric, and the third was regionally multicentric, with a popliteal artery-soft tissue component as well. All 3 of these patients died with metastases in various sites.