A randomised double-blind clinical trial was conducted on 106 patients scheduled for pulmonary resection. Patients received an epidural infusion containing 0.1%, 0.2% bupivacaine or saline in combination with fentanyl 10 microgram.ml -1. Adequacy of analgesia was assessed at rest and during movement over 24 h. Analgesic efficacy was assessed using visual analogue scores and an observer/verbal ranking scale. Pain scores were higher in the fentanyl-only group at the 2 h assessment (p < 0.05). Otherwise, there were no between-group differences in pain scores or in the total amounts of epidural solution used. All patients received continuous haemodynamic monitoring. There were no between-group differences in the number of episodes of hypotension or in the number of interventions for hypotension. However, the use of intra-operative vasopressor and the incidence of temporary neurological complications was higher in the 0.2% bupivacaine group (p < 0.05). We conclude that, in the early postoperative period, the addition of bupivacaine 0.1% improves fentanyl epidural analgesia in patients undergoing lung resection and is not associated with the disadvantages seen with the addition of bupivacaine 0.2%.