A trial had shown that acupuncture can cut headache rates by around a half.

Tension headache can be hard to treat effectively. But acupuncture may provide some relief, say researchers in Munich, Germany. They looked at a group of 270 patients, offering them either traditional Chinese acupuncture, minimal acupuncture or no treatment.

Those on traditional acupuncture had a fall in days with headache - seven days less over the four weeks following treatment. Those having minimal acupuncture, where needles were only inserted superficially into the skin, received nearly as much benefit, however. The findings suggest that acupuncture can be at least as good as standard treatment for relief of tension headache. The benefit of minimal acupuncture, where true acupuncture points are not actually treated, does seem to raise some questions as to how acupuncture really works.

Source
BMJ Online First 28th July 2005