Acupuncture treatment is frequently sought for tension-type headache (TTH), but there is conflicting evidence as to its effectiveness. This randomised, controlled, multicentre, patient-and observer-blinded trial was carried out in 122 outpatient practices in Germany on 409 patients with TTH, defined as > or =10 headache days per month of which < or =1 included migraine symptoms. Interventions were verum acupuncture according to the practice of traditional Chinese medicine or sham acupuncture consisting of superficial needling at nonacupuncture points. Acupuncture was administered by physicians with specialist acupuncture training. Ten 30-min sessions were given over a six-week period, with additional sessions available for partial response. Response was defined as >50% reduction in headache days/month at six months and no use of excluded concomitant medication or other therapies. In the intent-to-treat analysis (all 409 patients), 33% of verum patients and 27% of sham controls (p=0.18) were classed as responders. Verum was superior to sham for most secondary endpoints, including headache days (1.8 fewer; 95% CI 0.6, 3.0; p=0.004) and the International Headache Society response criterion (66% vs. 55% response, risk difference 12%, 95% CI: 2%-21%; p=0.024).). The relative risk on the primary and secondary response criterion was very similar ( approximately 0.8); the difference in statistical significance may be due to differences in event rate. TTH improves after acupuncture treatment. However, the degree to which treatment benefits depend on psychological compared to physiological effects and the degree to which any physiological effects depend on needle placement and insertion depth are unclear.