There are many studies that support acupuncture. Some are good, some are large, but when you do a good, large study the results vanish. A common trick when results fail to appear is to concludethat since the placebo results were as good as the actual treatment, the placebo must be effective as well!
http://www.sciencebasedmedicine.org/...ure-revisited/
http://whatstheharm.net/acupuncture.html
One problem is that many acupuncturists do not grasp that there's a need for keeping needles sterile. And if they practice what they preach, they shouldn't think so - after all, diseases are caused by disrupted energy flow along the meridians, not by bacteria or viruses. So abscesses and transfer of blood-borne diseases are rather common compared to when you go to a real hospital.