Background. Acupuncture is often used for primary dysmenorrhea. Objective. To assess the efficacy of a single point of acupuncture in the management of primary dysmenorrhea compared with sham acupuncture and no acupuncture. Methodology. Patients with primary dysmenorrhea were randomly assigned to acupoint group (n = 50), unrelated acupoint group (n = 50), nonacupoint group (n = 46), or no acupuncture group (n = 48). Acupuncture and sham acupuncture were administered once-daily for 3 days with electro-acupuncture at Sanyinjiao (SP6) that was specifically designed to treat primary dysmenorrhea, or an unrelated acupoint (Xuanzhong, GB39), or nonacupoint location. The primary outcome was pain intensity as measured by a 100-mm visual analog scale (VAS) at baseline; 5, 10, 30, and 60 minutes following the start of the first intervention. Cox retrospective symptom scale (RSS), verbal rating scale (VRS), pain total time, and proportion of participants using analgesics were also recorded during three menstrual cycles. Results. The primary comparison of VAS scores demonstrated that patients receiving acupuncture (-15.56 mm, 95% CI -22.16 to -8.95, P < 0.001), unrelated acupoint (-18.14 mm, 95% CI -24.81 to -11.47, P < 0.001), and nonacupoint (-10.96 mm, 95% CI -17.62 to -4.30, P = 0.001) treatment presented significant improvements compared with no acupuncture group. There were no significant differences among the four groups with respect to secondary outcomes. Conclusion. Acupuncture was better than no acupuncture for relieving the pain of dysmenorrhea following a single point of acupuncture, but no differences were detected between acupoint acupuncture and unrelated acupoint acupuncture, acupoint acupuncture and nonacupoint acupuncture.