Whether acupuncture is efficacious or a placebo has been the subject of ongoing scientific research. Scientists have conducted reviews of existing clinical trials according to the protocols of evidence-based medicine; some have found efficacy for headache, low back pain and nausea, but for most conditions have concluded that there is insufficient evidence to determine whether or not acupuncture is effective. The WHO, the National Center for Complementary and Alternative Medicine (NCCAM) of the National Institute of Health (NIH), the American Medical Association (AMA) and various government reports have also studied and commented on the efficacy of acupuncture. There is general agreement that acupuncture is safe when administered by well-trained practitioners, and that further research is warranted.

Traditional Chinese medicine's acupuncture theory predates use of the scientific method, and has received various criticisms based on scientific thinking. There is no physically verifiable anatomical or histological basis for the existence of acupuncture points or meridians. Proponents reply that TCM is a prescientific system that continues to have practical relevance. Acupuncturists tend to perceive TCM concepts in functional rather than structural terms, i.e. as being useful in guiding evaluation and care of patients.