In the present study, we examined the effects of preoperative electroacupuncture (EA) at classical bilateral acupuncture points (Zusanli, also known as ST-36) on postoperative pain and opioid-related side effects. One hundred healthy consenting women undergoing lower abdominal surgery were randomly assigned to four treatment regimens: Group I (n=25), control; Group II (n=25), sham-EA (needle insertion without electrical stimulation); Group III (n=25), low-EA (2 Hz of electrical stimulation); and Group IV (n=25), high-EA (100 Hz of electrical stimulation). EA groups received needle insertion with or without electrical stimulation 20 min prior to anesthesia. All patients received patient-controlled analgesia (PCA) of morphine postoperation. Postoperative pain was evaluated by recording (1). the time of the first required analgesic, (2). the number of PCA demands, (3). the total amount of morphine required by PCA, and (4) patients' VAS pain score. We found that the time of first analgesic requested was 10, 18, 28, and 28 min in the control, sham-, low-, and high-EA groups, respectively. During the first 24h, the total amount of morphine required was decreased by 21, 43 and 61% in the sham-, low- and high-EA groups, respectively. The incidence of nausea and dizziness during the first 24h after surgery was significantly reduced in both the low-EA and high-EA groups compared with the control and sham-EA groups. We also found that sham-EA exerts a beneficial effect with respect to its pain relieving quality but not the side effect profiles. Our findings demonstrates that preoperative treatment with low-EA and high-EA can reduce postoperative analgesic requirements and associated side effects in patients undergoing lower abdominal surgery.