We have discussed the pathological and clinical features in eleven examples of a distinctive type of benign tumor of bone. These tumors are characterized by a prominent network of osteoid trabeculae showing varying degrees of calcification and a vascular stroma which fairly frequently contains benign giant cells and little fibrous tissue. Because of their histological features we feel that they most closely resemble osteoid osteomata. Their biological behavior indicates a distinct difference from this lesion, however, and we suggest the designation "giant osteoid osteoma".