We explored reasons for the failure of patients to recall major portions of the information on consent forms and in oral explanations about consent. Within one day of signing consent forms for chemotherapy, radiation therapy, or surgery, 200 cancer patients completed a test of their recall of the material in the consent explanation and filled out a questionnaire regarding their opinions of its purpose, content, and implications. Only 60 per cent understood the purpose and nature of the procedure, and only 55 per cent correctly listed even one major risk or complication. We found that three factors were related to inadequate recall: education, medical status, and the care with which patients thought they had read their consent forms before signing. Only 40 per cent of the patients had read the form "carefully." Most believed that consent forms were meant to "protect the physician's rights." Although most thought that consent forms were necessary and comprehensible and that they contained worthwhile information, the legalistic connotations of the forms appeared to lead to cursory reading and inadequate recall.