Many different styles of acupuncture practice exist, and lack of agreement on the optimal acupuncture treatment for any particular condition may mean that some patients do not receive the best treatment. This uncertainty also makes the negative results of sham controlled trials difficult to interpret. Unless we can be sure that both adequate acupuncture and an inactive sham were used in a particular trial, then that trial should not be interpreted as dismissing acupuncture for that condition. Acupuncture practice clearly involves much more than needling procedures, but there is a strong argument for elucidating the role of those needling procedures first. The components of acupuncture needling procedures have been described in the STRICTA document, but it is also clear that the patient's perception of needling is relevant for the outcome of treatment. We therefore recommend the concept of 'dose' of acupuncture needling, which should include both the stimulus given to the patient, and certain aspects of the patient's perceptions and response that are known to be linked to the subsequent therapeutic response. We propose the following definition of dose: the physical procedures applied in each session, using one or more needles, taking account of the patient's resulting perception (sensory, affective and cognitive) and other responses (including motor). The dose may be affected by the state of the patient (eg nervous, immune and endocrine systems); different doses may be required for different conditions. The constituents of an adequate dose can be established initially by clinical opinion and subsequently by empirical evidence from experimental studies, which may be either clinical or basic research studies. Systematic reviews which do not consider the adequacy of the acupuncture treatment may have unreliable conclusions. Out of 47 recent systematic reviews, only six have applied some criteria for adequacy. Five used a rating system or conducted a subgroup analysis, and one excluded studies from the analysis altogether if they did not meet criteria for adequacy. Research into what constitutes an adequate dose of acupuncture has long been neglected and is now urgent. Clinical studies that compare the effects of different treatment protocols are probably the most reliable source of evidence, and may also demonstrate a dose-response relationship.