Objective: This study was undertaken to systematically assess and summarize the effects of acupuncture on cortisol secretion. Materials and methods: We searched articles published up to May 2010 in six electronic databases (PubMed, Cochrane Library, KISS, KISTI, DBPIA, Kyobo Scholar). Randomized clinical trials (RCTs) which met all the inclusion criteria were reviewed. Eight RCTs were finally selected for this systematic review and assessed by three reviewers. The risk of bias was also estimated by using the Cochrane criteria. Results: Six RCTs reported no distinct difference of cortisol levels between control and experimental groups. Two RCTs reported significant differences of cortisol levels between groups; one reported the acupuncture group with markedly higher concentrations of cortisol while the other reported the opposite result. Conclusion: There are some difficulties in clearly identifying the effects of acupuncture on cortisol levels in this systematic review due to inconsistent results. Therefore, more rigorous trials with larger scales need to be conducted to clarify the effects of acupuncture on cortisol levels.