SummaryA double-blind, randomized trial was carried out in 90 patients to compare the analgesic and anti-inflammatory efficacy of 500 mg diflunisal twice daily with that of 25 mg codeine phosphate 4-times daily and of placebo in relieving pain and swelling after surgical removal of impacted third molars. Diflunisal was found to be superior to codeine and placebo on the first post-operative day, but the difference in efficacy of the drugs had diminished by the third post-operative day. In the diflunisal group of 30 patients, 10 (33%) developed‘dry socket’or alveolitis sicca dolorosa. Only 2 patients in the codeine group and 1 patient in the placebo group developed this very painful condition. The possible explanation of‘dry socket’is discussed.