Background: Primary dysmenorrhea (PD), is one of main gynecological complaints in women of child-bearing age. Common medications for PD do not always achieve satisfactory outcome of pain relief. Hence, both health professionals and patients are seeking help from complementary and alternative medicine. The acupoint herbal plaster (AHP), which appears to be a safe and effective way to alleviate menstrual pain, as well as to improve other PD-related symptoms. Despite similar clinical studies for this condition in the past, no highquality methodology-based clinical trial has been reported to date. The current study aims to assess the efficacy of the AHP compared with the acupoint placebo plaster (APP) and being placed on a waiting-list control group in patients with primary dysmenorrhea. Methods/design: This study is a randomized, single-center, placebo-controlled clinical trial. A total of 180 women with PD will be included and randomly allocated to the AHP, APP and waiting-list (WL) groups in a 1:1:1 ratio. Patients in the AHP group will be provided with herbal plasters (Shaofuzhuyu decoction) on various acupoints: Shenque (CV8), Guanyuan (CV4), Qihai (CV5), Ciliao (BL32) and Zigong (EX-CA1). Women in the APP group will receive placebo plasters on the same acupoints, and no intervention will be given to the WL group until completion of the study. The primary outcome will be pain intensity reduction measured by a Visual Analog Scale (VAS), with other outcome measurements including the Cox Menstrual Symptom Scale (CMSS), the 12-Item Short Form Health Survey (SF-12) and the Participant Global Impression of Change (PGIC). All assessments will be performed at baseline, each menstrual cycle during the treatment course and the follow-up course. Any adverse events will be recorded throughout the study. Discussion: This is the first study to compare the changes in menstrual pain after three different interventions: the active intervention (AHP), the placebo intervention (APP), and a period of no intervention (WL). This three-arm randomized controlled trial (RCT) aims to investigate the relative contributions of the specific (AHP vs. APP) and nonspecific (APP vs. WL) effects to the overall clinical effects of the active AHP on women with PDM. The scientific and rigorous methodology design of this trial should gather good evidence to assess the curative effects and safety of the AHP on PD. Moreover, the results of this study may provide evidence-based references for the treatment of menstrual pain in future.