The primary aim of this survey was to establish from acupuncture patients the type and frequency of adverse events they experienced and attributed to their treatment. Secondary aims included the measurement of patient-reported adverse consequences arising from advice received about conventional/prescribed medication or from delayed conventional diagnosis and treatment. A postal survey was conducted of prospectively identified acupuncture patients. One in three members of the British Acupuncture Council (n = 638) invited consecutive patients to participate in the survey. Participating patients gave baseline data and consented to direct follow-up by the researchers at 3 months. A structured questionnaire was used to collect data on perceived adverse events. A total of 9408 patients gave baseline information and consent, and 6348 (67%) completed 3-month questionnaires. Responders were not dissimilar to non-responders for all known characteristics. Six hundred and eighty-two patients reported at least one adverse event over 3 months, a rate of 107 per 1000 patients. Three patients reported a serious adverse event. The most common events reported were severe tiredness and exhaustion, pain at the site of needling and headache. Patients receiving acupuncture treatment that was not funded by the NHS and patients not in contact with a GP or hospital specialist were less likely to report adverse events. One hundred and ninety-nine (3%) of responding patients reported receiving advice about conventional/prescribed medication, six of whom reported adverse consequences after taking the advice. Two patients reported delayed conventional treatment.