Slowly growing brain tumors may not present specific symtoms or signs related to increased intracranial pressure due to volume-spacial compensation. So we may not find brain tumors in patients in preoperative evaluations. But patients with unknown brain tumors may have severe complications after anesthesia. We experienced a patient whose emergence was delayed from general anesthesia for laparascopic urinary incontinence surgery (Burch's operation). The patient had such neurologic signs as deeply confused mentality, loss of pupil reflex and anisocoria. A large brain tumor in the left parietal lobe was revealed by brain MRI and it was resected. After further evaluation we found that it had originated from pulmonary adenocarcinoma, so the patient was designated for radiation therapy.