An analysis of 6 patients with periosteal osteosarcoma treated by the authors along with a review of 55 patients reported in the literature demonstrates that periosteal osteosarcoma is distinctly different from conventional osteosarcoma or periosteal chondrosarcoma. Periosteal osteosarcoma is a less aggressive tumor than conventional osteosarcoma. It is a relatively well-differentiated chondroblastic osteosarcoma occurring on the surface of the long bones of the extremities. Three patients demonstrated frank medullary invasion of tumor, two grossly and one microsurgically. Patients treated with marginal resection had a 70% local recurrence rate. Patients receiving wide resection or primary amputation have survived longer with less recurrence of disease. Overall, 10 of 61 patients are dead with metastatic disease with a mean reported follow-up of 6 years and 7 months. Adjunctive therapy has been of no demonstrable aid in terms of prolonging survival. Medullary extension of this tumor should not be used to exclude this diagnosis. The authors believe that the treatment of choice is wide resection without adjunctive chemotherapy.