Background: Chronic neck and shoulder pain is common and disabling. Objective: The aim of this study was to compare the effectiveness of electro-acupuncture and transcutaneous electrical stimulation (TENS) for relief of shoulder and neck pain. Materials and Methods: Design: This was a randomized crossover trial. Subjects: Ninety patients were enrolled, with a mean age of 34 years, and with females slightly outnumbering males. All subjects completed the study. Intervention: For electro-acupuncture, acupuncture needles were placed in four different acupoints in the trapezius muscle and each subject underwent a 15-minute session of low-frequency electrical stimulation. TENS treatment was similar and used as an active comparator, with a 2-week washout period between treatments. Outcome Measures: The primary outcome was reduction in pain as measured by a 100 cm visual analogue scale. Secondary outcomes included quality-of-life (QoL) measures. Results: Electro-acupuncture produced significantly greater reduction in pain than TENS did the first 2 days after treatment (p=0.001 and p=0.003, respectively), with pain decreasing from 56 to 33 and 34 versus from 55 to 42 and 42. Electro-acupuncture also produced a significant improvement in the vitality subscale of the Short Form-36. No adverse effects or carryover effect were detected. Conclusions: The results of this study offer preliminary evidence for the comparative effectiveness of electro-acupuncture over TENS for the acute relief of chronic shoulder and neck pain in adults. © Copyright 2012, Mary Ann Liebert, Inc.