We have studied the influence of two different speeds of injection on the spread of spinal anaesthesia of bupivacaine in 40 orthopaedic patients. In a random order, 0.5% plain bupivacaine 3 ml was administered in 10 or 180 s into the subarachnoid space using a 27-gauge needle with the patients in a lateral horizontal position. The slower speed produced a higher spread of spinal anaesthesia (median difference 2.5 segments, P < 0.05).