On a national scale in Canada, the members of the Canadian Association of Radiologists, Section of Radiation Oncology, plan to continue their outcome analyses. Nevertheless, there is considerable activity within many of the cancer centers in establishing quality assurance for all aspects of clinical practice, not just related to the technique of radiation therapy. Studies from the Princess Margaret Hospital will be used as examples to illustrate the need for quality assurance in: (a) diagnosis and evaluation of patients; (b) decision making with respect to treatment; (c) technical components of radiation therapy; and (d) outcome analysis, particularly an analysis of failures. For the future, there are two major objectives related to quality assurance. One is related to those patients with cancers who have a high probability of being cured. In this situation, achieving optimal treatment must be the objective and quality assurance must be directed at determining what is optimal treatment. For those patients in whom cure is still not commonly reached, the objective will be to determine why failures are occurring and whether radiation therapy technique can decrease the relapse rate.