Much has been said about the importance of informed consent in Japan, but informing cancer to the patient has not been popular so far. We, as anesthesiologists, often treat pain in cancer patients, who occasionally, are not informed about the cancer. And we sometimes have patients with whom cautious consulting is necessary. This report presents our experience with a patient uninformed about the cancer but suspicious of his lung cancer. We met him as anesthesiologists, and this made the patient convinced that he had a cancer and was about to die soon.