Study Objective: To compare three analgesic regimens for pain relief after thyroidectomy. Design: Randomized, double-blind, placebo-controlled study. Setting: Inpatient anesthesia in a university department of endocrine surgery. Patients: 342 patients scheduled for elective thyroidectomy with nitrous oxide-oxygen-isoflurane anesthesia in addition to fentanyl. Interventions: Group 1 received preoperative oral controlled release morphine 10 mg and Group 2 received postoperative sublingual buprenorphine 0.2 mg. Group 3 received 0.25% bupivacaine (10 mi) wound infiltration before shin closure. Eight hours after tracheal extubation, patients received a second dose of the same drug in each group except in Group 3, where medication was changed to sublingual buprenorphine 0.2 mg. Measurements and Main Results: Patients in Group 2 required fewer additional analgesics: 0.54 +/- 0.68 vs. 0.96 +/- 0.84 in Group 1 and 0.79 +/- 0.78 in Group 3. Patients in Group 2 demonstrated a better pain score and this group showed a higher percentage of satisfied patients: 96% vs. 85% in Group 1 and 91% in Group 3. Group 2 also included more patients requiring no analgesics: 56% a. 32% in Group 1 and 42% in Group 3 The side effects in all three groups did not differ. Conclusion: The administration of sublingual buprenorphine after thyroidectomy provides better analgesia than small doses of oral controlled-release morphine or than 0.25% bupivacaine wound infiltration at the end of surgery. (C) 1997 by Elsevier Science Inc.