Introduction: Postoperative pain is one of the most common physiological and psychological stress in patients that disrupts body function and can endanger patients’ health. This study aims to determine the effect of aromatherapy with Citrus aurantium essential on pain after orthopedic surgery. Methods: This randomized clinical trial was performed on 60 candidates for orthopedic surgery. Patients were selected through convenience sampling and divided into intervention and control groups through randomized block allocation. If the visual analogue scale (VAS) score was above 3, patients in the intervention group received aromatherapy with C. aurantium essential and the patients in the control group received a placebo (almond oil). VAS was used to measure pain. Data analysis was performed using independent t test, paired t test, and analysis of variance with repeated measures using SPSS software version 13. Results: Mean (SD) of pain intensity after intervention in experimental and control groups within 4, 8, and 12 hours after surgery was 7.30 (1.23) vs. 7.90 (0.99), 5.30 (0.98) versus 5.53 (0.68) and 2.53 (0.9) vs. 3.60 (0.77) respectively. The findings indicated that there was a significant difference in mean pain intensity between the experimental and control groups at 4 and 12 hours after surgery. Use of analysis of variance with repeated measures test with taking into account the interaction of time and group also showed a significant difference in mean pain intensity between the two experimental and control groups. Conclusion: Aromatherapy with Citrus aurantium essential can be effective in reducing mild to moderate pain after orthopedic surgery. Further studies are recommended to confirm this finding.