Researchers should strictly consider the participants’ rights. They are required to document such protections as an ethical approval of the study proposal, the obtaining “informed consent”, the authors’ “conflict of interests”, and the source of “financial support” in the published articles. The purpose of this study was to assess the frequency of reporting ethical issues in human subject articles published in Iranian medical journals during 2009–2013. In this cross-sectional study, we randomly reviewed 1460 human subject articles published in Iranian medical (...) journals during 2009–2013 in two Persian and English language groups. Data collection was carried out by assessing articles, focusing on the documentation “ethics committee approval”, patients’ “informed consent”, “financial support”, “confidentiality”, and “conflict of interest”. Of 1460 evaluated articles, 443 reported “ethics committee approval”, 686 reported “informed consent”, 594 reported “financial support”, and 341 reported “conflict of interest”. 13% of the articles referred to patients’ confidentiality in their text. There was a significant association between these ethical documentations and the year of publication. Articles published in English language journals reported “ethics committee approval”, “financial support”, and “conflict of interest” significantly more than Persian language journals, but the frequency of “informed consent” was similar. Ethical documentation rate in Iranian medical journals is not up to the expected standards of reputable journals which might be related to a lack of awareness and the education of the authors and the journal’s editors. Precise reporting of ethical considerations in medical articles by authors are recommended. It is suggested journals and policymakers pay more attention to reporting this issue while providing standard guidelines in this regard. (shrink)