The aim of this study was to assess the adverse effects of acupuncture during a normal treatment routine. A total of 13 general practitioners and outpatient clinics and 16 other practitioners were included in a questionnaire survey in Germany. Patient gender and age, indications for and method of treatment and adverse effects were documented by the therapists. Altogether 409 patients receiving 3535 acupuncture treatments were included. Adverse effects were observed in 402 treatments (11.4%) in 153 different patients. The main side-effects were slight haemorrhage (2.9%), haematoma (2.2%), dizziness (1%) and other systemic symptoms (2.7%). Other side-effects mentioned (all below 1%) were fainting, nausea, prolonged de qui effect (paraesthesia) and increase of pain. In one case, aphasia was reported lasting 1 h after acupuncture.