OBJECTIVE: To compare the efficacy and safety of two analgesics (tramadol and ketorolac) for initial emergency treatment of renal colic. METHODS: A prospective study on 48 patients randomly assigned to treatment with ketorolac 30 mg i.m. and tramadol 1 mg/kg s.c. Pain intensity was evaluated by a simple analogic scale ranging from 0-4 (0 = no pain, 1 = mild, 2 = moderate, 3 = severe and 4 = very severe pain). Statistical analyses were performed with Student's test and the chi square test for numerical and qualitative data, respectively. RESULTS: No significant differences were found for the overall efficacy (> 80%) or side effects in both groups. However, a difference was found between both groups for pain score 15 minutes post-injection, which showed i.m. ketorolac to be more effective. CONCLUSION: Both ketorolac (30 mg i.m.) and tramadol (1 mg/kg s.c.) are effective in the initial treatment of renal colic. Both drugs have an efficacy greater than 80% when used separately and almost 100% when used in combination. The analgesic effect of ketorolac is observed earlier than that of tramadol.