Considering the accumulating evidence supporting that what information is given to participants before trial can affect their expectation and behavior both in positive (i.e. placebo effect) and negative (i.e. nocebo effect) ways [5–8], and that at the same time, success of blinding ensures minimizing risk of bias in a trial, the importance of information in PILs cannot be disregarded. Moreover, unlike PILs from conventional drug trials that accurately disclose the use of placebo , PILs of randomized placebo-controlled trials of acupuncture seem to vary in the way they describe placebo controls . There have been few empirical studies examining PILs of randomized placebo-controlled trials , and to our knowledge, the link between placebo information in PILs and results of blinding success or study outcomes has rarely been explored.