This study is based on 41 cases of parostesl (or juxta cortical) osteogenic sarcoma, which the authors prefer to define as periosteal osteosarcoma. The clinical features, radiological and histological characteristics are analysed. Treatment and prognosis are discussed. The treatment usually indicated is amputation, but in selected cases radical segmental resection is appropriate. The prognosis is comparatively favourable if the correct surgical treatment is carried out without delay.