OBJECTIVE: To investigate the clinical effectiveness and cost-effectiveness of acupuncture in patients with dysmenorrhea. STUDY DESIGN: In a randomized controlled trial plus non-randomized cohort, patients with dysmenorrhea were randomized to acupuncture (15 sessions over three months) or to a control group (no acupuncture). Patients who declined randomization received acupuncture treatment. All subjects were allowed to receive usual medical care. RESULTS: Of 649 women (mean age 36.1 +/- 7.1 years), 201 were randomized. After three months, the average pain intensity (NRS 0-10) was lower in the acupuncture compared to the control group: 3.1 (95% CI 2.7; 3.6) vs. 5.4 (4.9; 5.9), difference -2.3 (-2.9; -1.6); P<.001. The acupuncture group had better quality of life and higher costs. (overall ICER 3,011 euros per QALY). CONCLUSION: Additional acupuncture in patients with dysmenorrhea was associated with improvements in pain and quality of life as compared to treatment with usual care alone and was cost-effective within usual thresholds.