The use of complementary and alternative medicine is increasing in the Western world. However, there is no clear evidence of effect of alternative therapies. Moreover, there is no consensus between practitioners and researchers as to the right way of assessing the efficacy of alternative therapies. To investigate practitioners' perspective on evidence and ways of assessing efficacy twelve in-depth interviews were conducted in Denmark with acupuncturists, including physicians practising acupuncture, acupuncturists with a health-related background, and acupuncturists without a health-related background. Two themes predominated the study, first, the interviewees' general reflections on how it is possible to establish knowledge about an effect of acupuncture; and second the interviewees' reflections on the use of randomized controlled trials in acupuncture, including obstacles and alternatives to conducting randomized controlled trials. Further, two conceptions of what constitutes evidence were identified: a biomedical conception and an experience-based conception. Most interviewees were sceptical about the use of randomized controlled trials in acupuncture. Two reasons, especially, were given for this scepticism. First, practical and instrumental reasons concerning the specific elements of the randomized controlled trial or relating to limited resources; and second, value-based reasons are concerning the nature of acupuncture. However, the interviewees were really opposed only to a certain kind of randomized controlled trial, the so-called explanatory trial. They would actually welcome a pragmatic trial. The study gives valuable insight into an under explored field and provide a platform for further investigation, and a better informed discussion of the subject.