||BACKGROUND AND OBJECTIVES: Opioid use disorder (OUD) is a chronic disease with significant personal, societal, and public health consequences. Even for the minority who receive the most effective evidence-based treatments, morbidity, and mortality remain significant. These facts, along with the recovery movement calling for individualized, holistic, culturally sensitive care, have led to the exploration of adjunctive interventions including acupuncture. Despite hundreds of international trials, however, there is a lack of consensus regarding its efficacy in OUD due in large part to methodological issues of trials to date. In response to these issues, the National Acupuncture Detoxification Association (NADA) developed an operationalized manual auricular acupuncture protocol that has since become the most widely used in the US. This systematic review is the first to focus explicitly on randomized trials utilizing the NADA protocol as a complementary intervention to address OUD. METHODS: The methods utilized to identify studies for inclusion are based on a 2009 protocol developed by the Cochrane Collaboration. RESULTS: Four trials met inclusion criteria. Despite methodological issues, results indicate that while the NADA protocol may not be effective in reducing acute opiate craving or withdrawal, it may be effectively utilized as an adjunctive treatment to increase treatment retention and decrease methadone detoxification and maintenance dosages in OUD. CONCLUSION AND SCIENTIFIC SIGNIFICANCE: Incorporation of the NADA protocol into existing evidence-based treatment approaches may facilitate recovery and, through its impact on treatment retention and completion, indirectly impact morbidity, and mortality in individuals with OUD. Given the limitations of the current review, conclusions are tentative and directions for future research are discussed. (Am J Addict 2016;25:592-602).