Objective: To evaluate the postoperative analgesic efficacy in patients undergoing lumbar canal decompression using epidural morphine and clonidine at the Hospital Santa Casa de Vitória -ES, Brazil. Methods: Prospective, randomized study of 60 patients with stenosis of the lumbar canal up to two levels with surgical indication, in which decompression of the canal was performed in association with lumbar arthrodesis. In group 1 we performed conventional postoperative analgesia and in group 2, in addition to conventional analgesia, we associated epidural morphine and clonidine. We used VAS as a means of analyzing pain intensity at 1, 12, and 36 hours after surgery. The statistical analysis was performed using Microsoft Office/Excel and the software GraphPad Prism (San Diego, CA, USA). Results: The mean age of patients was 47 years, and 52% were female. The mean VAS in the first hour, 12th, and 36th hours after surgery in the control group was 5.44, 2.13, and 0.55 respectively. In the morphine-clonidine group it was 6.96; 2.21 and 0.60. Comparing one group with another in its absolute values through the Mann-Whitney test, as well as comparing the pain variations between the 1st and 12th hour (1h X 12h) and between the 12th hour and 36th hour (12h x 36h ) through Student's t test it became clear that there was no statistical difference between groups (p > 0.05). Conclusions: The addition of epidural morphine and clonidine to conventional analgesia is not beneficial to reduce postoperative pain in patients undergoing lumbar canal decompression.Keywords: Lumbar vertebrae; Analgesia, epidural; Morphine; Clonidine; Visual analog scale; Postoperative period. RESUMO