We conducted a randomised double-blind placebo-controlled single-centre study to compare the effect of preoperative ibuprofen 600 mg, diclofenac 100 mg, paracetamol 1 g with codeine 60 mg or placebo (Vitamin C 50 mg) tablets for relief of postoperative pain in 119 patients who had day case operations under general anaesthesia for removal of impacted third molars. Patients were given the tablets 1 h before operation. Pain was assessed using visual analogue scales and verbal rating scales preoperatively at 15 and 30 min and 1 and 3 h postoperatively. After they had gone home, patients were contacted by telephone at 6 and 24 h postoperatively to find out whether they had any adverse effects from the analgesics. There was no significant difference in the extent of postoperative pain among the four groups, but the placebo group had significantly shorter times before their first request for postoperative analgesics (median 17 min, range 14-90) than the diclofenac group (median 32, range 15-150). Preoperative analgesics at the stated doses are effective in providing immediate postoperative pain control after operations on third molars. There were, however, some side-effects including nausea, vomiting, headaches, and gastrointestinal discomfort, but there were no significant differences among the active analgesic groups with respect to adverse events either shortly after operation or at 6 or 24 h.