Objective" To observe the effect of transcutaneous electrical acupoint stimulation (TEAS) on nausea and vomiting (N&V) induced by patient controlled intravenous analgesia (PCIA) with Tramadol. Methods= Sixty patients who were ready to receive scheduled operation for tumor in the head-neck region and post-operation PCIA, aged 39-65 years, with the physique grades Ⅰ-Ⅱ of ASA, were randomized into two groups, A and B, 30 in each group. The pre-operation medication, induction of analgesia and continuous anesthesia used in the two groups were the same. TEAS on bilateral Hegu (LI4) and Neiguan (PC6) points was intermittently applied to the patients in group A starting from 30 min before analgesia induction to 24 h after operation, and the incidence and score of nausea and vomiting, antiemetic used, visual analogue scores (VAS), and PCIA pressing times in 4 time segments (0-4, 4-8, 8-12 and 12-24 h after the operation was finished) were determined. The same management was applied to patients in Group B, with sham TEAS for control. Results: The incidence and degree of N&V, as well as the number of patients who needed remedial antiemetic in Group A were less than those in Group B. The VAS score and PCIA pressing time were lower in Group A than those in Group B in the corresponding time segments respectively. Conclusion: TEAS could prevent N&V induced by PCIA with Tramadol.