An update of the adjuvant trial on osteosarcoma in Sweden comparing patients receiving natural interferon (IFN) alpha with a high-dose chemotherapy group and a nonadjuvant group is presented. The overall survival for the IFN group is 49%, for the chemotherapy group 54%, and for the nonadjuvant group 35%. Trial evaluation was complicated by group differences with respect to various clinicopathologic features of prognostic significance. The role of IFN in the treatment of osteosarcoma can still not be established.