Background: Postoperative gastrointestinal dysfunction (PGD) is one of the most common complications in patients undergoing major abdominal surgery. Acupuncture has been used widely in gastrointestinal diseases due to its effectiveness and minimally invasive nature. Objective: This study evaluated the efficacy of using transcutaneous electrical acupoint stimulation (TEAS) during the surgery and postoperative recovery in patients with gastric and colorectal surgery for improving postoperative gastrointestinal function. Design, setting, participants and interventions: A total of 280 patients undergoing abdominal surgery were stratified by type of surgery (i.e., gastric or colorectal surgery) and randomly allocated into the TEAS group (group T) or the sham group (group S). Patients in group T received TEAS at LI4, PC6, ST36 and ST37. Patients in group S received pseudo-TEAS at sham acupoints. The stimulation was given from 30 min before anesthesia until the end of surgery. The same treatment was performed at 9 am on the 1st, 2nd and 3rd days after surgery, until the recovery of flatus in patients. Main outcome measures: The primary outcome was the time to the first bowel motion, as detected by auscultation. The secondary outcomes included the first flatus and ambulation time, changes of perioperative substance P (SP), incidence of PGD, postoperative pain, postoperative nausea and vomiting (PONV) and some economic indicators. Results: The time to first bowel motion, first flatus and first ambulation in group T was much shorter than that in group S (P < 0.01). In patients undergoing colorectal surgery, the concentration of SP was lower in group T than in group S on the third day after the operation (P < 0.05). The average incidence of PGD in all patients was 25%, and the frequency of PGD was significantly lower in group T than in group S (18.6% vs. 31.4%, respectively; P < 0.05). TEAS treatment (odds ratio = 0.498; 95% confidence interval: 0.232-0.786) and type of surgery were relevant factors for the development of PGD. Postoperative pain score and PONV occurrence were significantly lower in group T (P < 0.01). Postoperative hospitalization days and the resulting cost to patients were greatly reduced in the TEAS group (P < 0.01). Conclusion: Perioperative TEAS was able to promote the recovery of postoperative gastrointestinal function, reduce the incidence of PGD and PONV. The concentration of SP was decreased by TEAS treatment, which indicates that the brain-gut axis may play a role in how TEAS regulates gastrointestinal function. Trial registration: Chinese Clinical Trial Registry, ChiCTR1900023263. Please cite this article as: Li WJ, Gao C, An LX, Ji YW, Xue FS, Du Y. Perioperative transcutaneous electrical acupoint stimulation for improving postoperative gastrointestinal function: A randomized controlled trial. J Integr Med. Perioperative transcutaneous electrical acupoint stimulation for improving postoperative gastrointestinal function: A randomized controlled trial. J Integr Med. 2021; 19(3): 211-218. (C) 2021 Shanghai Changhai Hospital. Published by ELSEVIER B.V. All rights reserved.