The study is a multicentre, randomised, double blind, placebo-controlled trial. 1000 patients undergoing elective total hip replacement surgery from 20 orthopaedic centres in Australia and New Zealand will be assigned to receive either ibuprofen (1200mg daily) or matching placebo in 3 divided doses for 14 days. Study treatment will be started postoperatively on the day of surgery. Patient should not receive any other NSAIDs, apart from low dose aspirin, during the 14-day treatment period, unless such treatment becomes definitely indicated, in which case the study treatment should be withdrawn and open label treatment provided. There will be no other changes to standard care.