The purpose of this study was to compare the use of 0.5% ropivacaine with 0.5% bupivacaine for axillary brachial plexus anaesthesia. Sixty-six patients undergoing upper limb surgery were enrolled in a double-blind, randomized, multicentre trial. Five patients were subsequently excluded for various reasons. Of the remaining patients, 30 received 40 ml of 0.5% ropivacaine and 31 received 40 ml of 0.5% bupivacaine. Brachial plexus block was performed by the axillary approach using a standardized technique with a peripheral nerve stimulator. Parameters investigated included the frequency, onset and duration of sensory and motor block, the quality of anaesthesia and the occurrence of any adverse events. The six principal nerves of the brachial plexus were studied individually. The frequency for achieving anaesthesia per nerve ranged from 70 to 90% in the ropivacaine group and 81 to 87% in the bupivacaine group. The median onset time for anaesthesia was 10 to 20 minutes with ropivacaine and 10 to 30 minutes with bupivacaine, and the median duration was 5.3 to 8.7h with ropivacaine and 6.9 to 20.3h with bupivacaine. Motor block was evaluated at the elbow, wrist and hand, and was completely achieved at a rate of 60 to 73% in the ropivacaine group and 55 to 71% in the bupivacaine group. The median duration of motor block was 6.5 to 7.5h with ropivacaine and 6.0 to 9.0h with bupivacaine. These parameters were not statistically different. The duration of partial motor block at the wrist (6.8 v 16.4h) and hand (6.7 v 12.3h) was significantly longer with bupivacaine. Ropivacaine 0.5% and bupivacaine 0.5% appeared equally efficacious as long-acting local anaesthetics for axillary brachial plexus block.