Objectives : To investigate the association of trial registration status with presence of reporting bias including publication bias and outcome reporting bias in recently published randomized controlled trials (RCTs) of acupuncture. Methods : A PubMed search for RCTs of acupuncture published from March 2016 to February 2017 was conducted. Primary outcomes were identified and the direction of the results was judged as positive (i.e., statistically significant) or negative. The trial registration was identified by manually screening the trial registration number in the main text of the published article and classified into 1) prospective registration; 2) retrospective registration based on the registration date or; 3) no registration. Results : Of the 125 included RCTs, only 40 studies (32.0%) prospectively registered the study protocols. Among 65 RCTs that adequately reported the primary outcome, unregistered trials were more likely to report positive results than the registered ones (p=0.013). Of the 40 prospectively registered studies, 19 trials (47.5%) had the discrepancies between the registered and published primary outcomes and furthermore, 40% of them reported the positive findings. Conclusions : Unregistered trials were more likely to report positive results and the discrepancies between the registered and published primary outcomes were detected in about a half of the prospectively registered studies, 42.1% of which tended to report positive findings. Journal editors and researchers in this field should be alerted to various reporting biases.