AbstractMethods of assessing and reporting toxic reactions induced by therapy, particularly chemotherapy, need improvements. Accurate and reliable reporting of therapyinduced toxicity will be necessary for quality clinical research including drug development and for implementation of complex multìmodality treatments, currently, however, the extent and quality of reporting of toxic reactions vary widely. Whereas standard and widely accepted criteria have been established for assessing and reporting therapeutic response, no such criteria exist for toxicity. We have developed comprehensive criteria for assessing and reliably reporting toxic reactions. We have reduced the degree of subjectivity in assigning grades by using primarily objective methods. An attempt has been made to standardize the“morbidity impact”of each toxicity grade irrespective of the organ system involved.