Thirty-eight consecutive patients who were admitted to the hospital for total joint replacement were studied to determine their understanding of the elements of informed consent at the time when they signed the consent document before the operation and their recall of those elements six months after the operation. All patients received instruction from the same patient-educator before the operation. Each patient was asked to respond verbally to a questionnaire about the preoperative instruction. If a question was not answered correctly, tutoring was given until the patient gave the correct response. The consent document was not presented for signature until the patient could answer all questions correctly. In an interview six months after the operation, thirty-six of the thirty-eight patients were asked the same questions that they had answered before the operation. The recall of risks and benefits six months after the operation was compared with the understanding of risks and benefits that had been demonstrated before the operation by both the verbal questioning and the signed consent document. At six months, the number of patients who recalled the risks ranged from nine (25 per cent) who remembered the risk of infection to only one who remembered the risk of damage to a nerve or artery. More patients recalled the potential benefits: eight (22 per cent) for relief of pain and improved function and five (16 per cent) for improved motion.