OBJECTIVE To evaluate the efficacy and tolerability of ketorolac tromethamine 10 mg and 30 mg suppositories in comparison to placebo, after single dose administration in patients suffering from post-operative pain after cholecystectomy. METHODS Double-blind, randomized, controlled study. METHODS Anaesthesia Service. METHODS 99 patients with severe pain following surgery. METHODS Cholecystectomy. RESULTS The analgesia activity of ketorolac tromethamine 10 mg and 30 mg suppositories were evaluated after single dose administration by assessing pain intensity and pain relief using a 4 point scale (VRS). At the end of the treatment period overall assessment of safety and efficacy were recorded by physician and patient. The results show that in both active groups after 30' and until 4 hours, pain intensity decreased significantly with respect to the baseline. However a statistically significant difference between groups of p < 0.02, p < 0.01 and p < 0.05 was found in favour of the 30 mg dose respectively at 30', 6 and 8 hours after administration. All the patients treated with placebo suppositories required another rescue analgesic drug and withdrew from the trial. Three patients complained adverse events not related to treatment: two on placebo and one on ketorolac 10 mg. The systemic and local tolerability of the drug was good. CONCLUSIONS This study shows that ketorolac 30 mg suppositories are effective in clinical conditions, such as after surgery, in which pain control must be achieved within the shortest time interval and maintained or improved by means of a single route of administration.