Breast surgery can be emotionally distressing and physically painful. Acute pain following surgery is often related mainly to the axillary surgery and is aggravated by arm and shoulder movement. We conducted a prospective double-blind, randomised, placebo-controlled trial to determine the influence of local anaesthetic irrigation of axillary wound drains on postoperative pain during the first 24 h following a modified Patey mastectomy (mastectomy with complete axillary node clearance). The treatment group received bupivacaine irrigation through the axillary wound drain 4-hourly for 24 h postoperatively. Controls received irrigation with normal saline. Morphine via a patient controlled analgesia pump was used for postoperative analgesia. Morphine consumption, visual analogue and verbal rating pain scores were recorded. There were no statistical differences in morphine requirements or pain scores between the two groups, nor were there differences in anti-emetic or supplemental analgesic consumption. Bupivacaine irrigation used in this manner does not appear to offer an effective contribution to postoperative analgesia.