We report a 68-year-old, American Society of Anesthesiologists Class I (ASA I), female patient scheduled for malignant uterine adnexal tumor surgery and revascularization for ovarian cancer. An epidural catheter was inserted at T12-L1 for 5 cm. Anesthesia was induced with remifentanil (0.25 microg x kg(-1) x min(-1)), sevoflurane (5%) and rocuronium (30 mg). Anesthesia was satisfactorily maintained after intubation with sevoflurane (1.5%) and remifentanil (0.2 microg x kg(-1) x min(-1)). We extubated the patient because spontaneous breathing and consciousness were observed. We intubated the patient immediately for apnea that occurred after extubation. The patient made an uneventful recovery after naloxone administration. In pharmacokinetic simulation, on the assumption that epidural administrated fentanyl was carried to blood content promptly, effect concentration to cause respiratory depression was not reached. Postoperative apnea was rationalized as follows; tardy respiratory depression with the epidural administration, and unexpected dosage of the residual fentanyl in the catheter.