Background: Duloxetine is an antidepressant that is also useful in chronic neuropathic and central origin pain. In this study, the role of duloxetine in decreasing acute postoperative pain after lumbar canal stenosis surgery is explored. Methods: In this single center, triple blinded, and placebo-controlled trial, 96 patients were randomized for statistical analysis. The intervention group received oral duloxetine 30 mg once a day (OD) for 2 days before surgery, 60 mg OD from the day of surgery to the postoperative second day and 30 mg OD for the next 2 days (a total duration of 7 days). A placebo capsule was given in the other group for a similar time and schedule. The same standard perioperative analgesia protocols were followed in both groups. Results: Total morphine consumption up to 24 hours was significantly decreased in the duloxetine group (p < 0.01). The time to the first analgesia requirement was similar in both groups but the time to the second and third dose of rescue analgesia increased significantly in the duloxetine group. The time to ambulation was decreased significantly (p < 0.01) in the duloxetine group as compared to the placebo group. Pain scores remained similar during most of the time interval. No significant difference was observed in the complication rate and patient satisfaction score recorded. Conclusions Duloxetine reduces postoperative pain after lumbar canal stenosis surgery with no increase in adverse effects.