- BACKGROUND: Auricular acupuncture is a promising method for postoperative pain relief. However, there is no evidence for its use after ambulatory surgery. Our aim was to test whether auricular acupuncture is better than invasive needle control for complementary analgesia after ambulatory knee surgery. METHODS: One hundred and twenty patients undergoing ambulatory arthroscopic knee surgery under standardized general anesthesia were randomly assigned to receive auricular acupuncture or a control procedure. Fixed indwelling acupuncture needles were inserted before surgery and retained in situ until the following morning. Postoperative rescue analgesia was directed to achieve pain intensity less than 40 mm on a 100-mm visual analogue scale. The primary outcome measure was the postoperative requirement for ibuprofen between surgery and examination the following morning. RESULTS: Intention-to-treat analysis showed that patients from the control group (n = 59) required more ibuprofen than patients from the auricular acupuncture group (n = 61): median (interquartile range) 600 (200-800) v. 200 (0-600) mg (p = 0.012). Pain intensity on a visual analogue scale was similar in both groups at all time points registered. The majority of patients in both groups believed that they had received true acupuncture and wanted to repeat it in future. INTERPRETATION: Auricular acupuncture reduced the requirement for ibuprofen after ambulatory knee surgery relative to an invasive needle control procedure.