Thirty patients who had undergone elective abdominal aortic surgery were studied in a prospective, randomised double-blind comparison of thoracic epidural 0.2% bupivacaine alone, thoracic epidural fentanyl alone and thoracic epidural 0.2% bupivacaine combined with fentanyl. Pain relief, pulmonary function, cardiovascular stability and side effects were assessed. Pain relief was excellent in the combined bupivacaine-fentanyl series, being significantly better than the other groups (p less than 0.05) during the entire study period and was not accompanied by hypotension. Forced expiratory parameters were reduced in all groups throughout the study to 50-60% of the pre-operative values, but there were no significant differences between groups. The incidence of side effects attributable to either epidural bupivacaine or fentanyl was low. This study supports the increasing use of epidural infusion analgesia for postoperative pain management after abdominal surgery.