In Germany, acupuncture is one of the most frequently used complementary and alternative therapies. In the year 2000, we initiated three large projects in co-operation with statutory health insurance companies to assess the effectiveness, safety and costs of acupuncture in patients with chronic headache, low back pain and pain due to osteoarthritis. Our findings showed that acupuncture was more effective than conventional standard treatment, treatment without acupuncture or a waiting list control. A significant difference between acupuncture and sham acupuncture was only seen for arthritis of the knee; for the other diagnoses, both forms of acupuncture showed similar effects. Whether the effects of acupuncture are due primarily to specific or unspecific mechanisms appears to depend on the diagnosis and should be investigated in further studies.