||Background Ondansetron, sometimes combined with acustimulation at PC6 (Neiguan), is commonly used for preventing postoperative nausea and vomiting, but PC6 is not the only point that can be used for this purpose. Objectives To evaluate the combined effects of ondansetron and ST36 (Zusanli) acupuncture point injection on postoperative vomiting (POV) after laparoscopic surgery. Methods A randomised, patient and assessor-blinded, placebo-controlled clinical study was conducted. One hundred and sixty patients undergoing laparoscopic surgery were randomly assigned to one of four groups: (1) group P (placebo-control): intravenous normal saline +bilateral non-acupuncture point injection of vitamin B1 (n=40); (2) group O (ondansetron): intravenous ondansetron+bilateral ST36 sham injection (n=40); (3) group A (acupuncture point injection): intravenous normal saline+bilateral acupuncture point injection at ST36 of vitamin B1 (n=40); (4) group C (combination): intravenous ondansetron+bilateral acupuncture point injection at ST36 of vitamin B1 (n=40). Interventions were made on arrival at the postanaesthesia care unit. The primary outcome was the incidence of POV within 24 h after the operation. Secondary outcomes included severity of vomiting, incidence of rescue treatment, patients' satisfaction and the first anal exsufflation time 24 h after the operation. Results The incidence of POV within 24 h postoperative period in each group was P 33%; O 11%, A 9% and C 6%. Outcomes for all intervention groups were significantly better than that for placebo (p<0.01). For the three interventions compared with placebo, the numbers needed to treat (NNTs) were O, NNT=5; A, NNT=5 and C, NNT=4. The secondary outcomes also demonstrated greater benefits of the combined regimen, with improvement seen in all the measures. Conclusions Ondansetron, acupuncture, and ondansetron and acupuncture combined are effective prophylaxis for POV.