Background: There are scanty data to apply radial extracorporeal shock wave therapy (rESWT) on the acupuncture points in the lower abdomen to reduce the menstrual pain. This trial aimed to test the rESWT safety and efficacy for treating primary dysmenorrhea (PD). Methods: Forty-four young-women with PD were randomly assigned to one of the three groups: to receive rESWT on the acupuncture points during the follicular phase (Group A, n = 15) or during the luteal phase (Group B, n = 14), or to apply heat patch to the acupuncture points during the follicular phase as the control (Group C, n = 15) over three menstrual cycles. The pain severity (using 0-to-10 visual analog scale), the pain duration (hours), plasma PGF 2α prostaglandin F2alpha and prostaglandin E2 (PGE 2 ), self-rating anxiety scale and menstrual blood loss were assessed before and after interventions. Results: The pain severity and duration significantly decreased in all groups after interventions. Although the reduced pain duration was not different among the groups, the reduced pain severity was more significant ( P = .003) in Groups A (−53.8 ± 33.7%) and B (−59.3 ± 36.7%) than in Group C (−18.7 ± 27.1%). The rESWT intervention did not change plasma prostaglandins in Group A, although there was a decreased prostaglandin F2alpha (−20.5 ± 32.9%) in Group B or a decreased PGE 2 (-18.9 ± 17.8%) in Group C. The anxiety level showed no change after intervention. The menstrual blood volume reduced slightly after intervention and the change of menstrual blood loss in Group B was significant ( P = .038). Conclusion: The rESWT applications on the abdominal acupuncture points safely and effectively reduced the menstrual pain, which was not associated with the prostaglandin changes. The rESWT-reduced pain seemed equally effective with the intervention applied during the follicular phase or luteal phase of the menstrual cycle. Heat patch placed on the abdominal acupuncture points also reduced the pain severity and duration, indicating that the improved blood flow could effectively alleviate the menstrual pain with PD. The changes in anxiety level and menstrual blood loss were slight after intervention.