1. Two cases of malignant hemangioendothelioma of bone are presented, and the world's literature is reviewed. In all, there are thirty-four adequately documented cases of this rare primary bone tumor. 2. The clinical and roentgenographic features are non-specific. 3. The histological characteristic of this lesion is an overproduction of atypical endothelial cells that frequently form anastomosing vascular clefts. 4. Prognosis and treatment are discussed.