OBJECTIVE: This study evaluated the effect of perioperative buccal acupuncture therapy on the incidence of postoperative delirium in elderly patients who underwent orthopedic lower limb surgery. METHODS: This was a single-center, prospective, randomized controlled trial. A total of 120 elderly patients (aged ≥65 years) scheduled for elective orthopedic lower limb surgery were randomly assigned to the intervention group (n = 60, buccal acupuncture 30 min before anesthesia induction until the end of surgery and for 30 min each day for the first 2 postoperative days) or the control group (n = 60, no buccal acupuncture). The primary outcome was delirium during the first 7 postoperative days. The secondary outcomes included delirium severity, duration, and subtype; intraoperative total consumption rate of sufentanil and remifentanil; interleukin-6, interleukin-8, and norepinephrine in venous blood; the total number of electronic analgesia pump compressions; nausea and vomiting in 48 h; postoperative pain score; postoperative hospital stay, and postoperative adverse event rates. RESULTS: The data of 120 patients were collected. The incidence of delirium during the first 7 postoperative days was significantly lower in the intervention group than in the control group (27 % [16/60] vs. 12 % [7/60]; relative risk, 0.44; 95 % confidence interval, 0.19-0.99; P = 0.037). Intraoperative total consumption rate of sufentanil and remifentanil, postoperative pain scores, and the incidence of postoperative nausea and vomiting were significantly lower in the intervention group. CONCLUSION: Buccal acupuncture can reduce the incidence of postoperative delirium in elderly patients who undergo orthopedic lower limb surgery.