The effect of lidocaine and bupivacaine on postoperative pain were compared in a double blind crossover study. Diflunisal (500 mg) was used as an analgesic and given before commencement of the surgical procedure.Bilateral impactions of lower third molars were removed on two occasions, four weeks apart, in a sample of 26 Chinese patients. One local anesthetic was used on one occasion and the alternate on the second. Pain intensity was indicated on a visual analogue scale hourly for eight hours, beginning one hour after the start of surgery.Pain at each postoperative hour was lower after bupivacaine and more patients indicated little or no pain after bupivacaine than after lidocaine. This was not reflected in patients' preference: 12 preferring lidocaine, 11 bupivacaine, and 3 indicating no preference, an important reason being a shorter period of numbness with lidocaine.Although diflunisal was given preoperatively, the postoperative course was not complicated by alveolitis in any case.While bupivacaine plus diflunisal resulted in less postoperative pain than lidocaine plus diflunisal, some patients were willing to sustain some pain after oral surgery if sensation was regained sooner.