This report describes a giant-cell tumor which arose in the tibia of a twenty-seven-year-old woman and did not involve the epiphysis. The tumor was composed of plump, spindle-shaped cells and giant cells, and had the histological appearance typical of giant-cell tumors. It did not contain areas of hemorrhage, hemosiderin pigment, osteoid, bone, or significant amounts of collagen. The lesion also did not have the fibrotic, scarred appearance of a fibrous cortical defect, reparative granuloma, or brown tumor of hyperthyroidism, the lesions it most closely resembled. The patient had no detectable parathyroid dysfunction. The clinical, roentgenographic, and histological features of other osseous lesions which may contain giant cells were not present.