BACKGREOUND: The aim of this study was to compare the pre-emptive effect of preoperative with postoperative tiaprofenic acid in adult local tonsillectomy. METHODS: We compared in forty adults the effect of preoperative with postoperative tiaprofenic acid on pain after tonsillectomy in a double-blind, randomized study, which was approved by the Ethics Committee. Informed consents were obtained. Patients were allocated randomly to receive a tiaprofenic acid (200 mg) intravenously either before (n=20) or immediately after (n=20) surgery. Postoperative pain was rated by self-rating visual analog scale for the first 24 hours. Tiaprofenic acid (200 mg) was given when patient complained pain. Time to the first analgesic administration, total requirement of analgesics for 48 hours and the first time of swallowing 100 ml water were checked. RESULTS: Postoperative 1 hour pain score of the preoperative group was significantly lower than postoperative groups (p<0.05). Times to the first analgesic administration, the total requirement of analgesics for 48 hours and the times of the first swallowing of 100 ml water were not significantly different between the two groups. CONCLUSIONS: Preoperative intravenous tiaprofenic acid (200 mg) in adult local tonsillectomy was effective on the reducing the intensity of the postoperative pain only 1 hour after operation. The use of preoperative tiaprofenic acid in adult local tonsillectomy was associated with a more calm recovery. The results of this study do not support the theory of preemptive analgesia.