Our study evaluated 116 surgical patients with cancer who received postoperative epidural analgesia with bupivacaine (BUP) (0.1%) and morphine (MS) (0.01%) during 5 days after epidural-light general anesthesia. Patients in group I (n = 17) were taking opioids in doses larger than 50 mg of morphine daily for 3 mo or more, whereas patients in group II (n = 99) were opioid-naive. Postoperative epidural infusions were started at 10 mL.h-1 for group I and 5 mL.h-1 for group II. All patients were evaluated every 6 h for pain, withdrawal, and overdosing. Dynamic pain scores were kept below 4/10 by titrating infusions and/or giving intravenous (IV) MS 4 mg every hour as needed. Fifteen patients were taking opioids for 3-6 mo and the remainder for more than 6 mo. Mean oral MS preoperative usage for group I was 183 mg (90-360 mg range). All patients experienced adequate analgesia. Group I required more epidural (137 vs 44 mg) and IV (48 vs 10 mg) MS and had a longer requirement for analgesic therapy (9 vs 3 days) when compared with group II. Daily epidural and IV MS usage were always more for group I by two- to threefold. No patient experienced respiratory depression or opioid withdrawal during the hospitalization. Thus, epidural BUP-MS appears to provide adequate postoperative analgesia while preventing withdrawal in opioid-dependent patients, if three times the normal dosage and duration of therapy are employed.