The thirty-seven cases of osteosarcoma examined with CT was evaluated. CT images were analyzed on the base ofthe itramedullary extension, cortical destruction, intralesional calcificatin, extension to either the epiphysisor adjacent joint, and soft tissue extension including muscular invasion and neuro-vascular invasion, And theseresults were compared with the feature detected on plain radiographs. The assessment of the itramedullaryextension 2.27cm over the measurement of the lesion on plain radiograph, and one skip metastasis on the distalfemur in the patient with osteosarcoma on the plain radiograph, and one skip metastasison the distal femur in thepaitient with osteosarcoma on the proximal tibia. CT could depict the involvement of the epiphysis and joint; however, for the diagnosis and the assessment of either cortical destructin of intralesional calcification, CT wasnot superior to plain radiogarphs significantly. CT provide valuable information about the soft tissueinvolvemeent, specifically sparing of the neurovascular bundle (82%). However, in the remaining 10 cases (28%), itdid not differentiated the invasion of neurovascular bundle from the only close contact of mass to neurovascualrbundle. CT proved to be a valuable method to assess the intraosseous and exteraosseous extent. particulary inplanning limb salvage procedure.