AbstractSystematic reviews (SR) may potentially contain reports of primary trials with ethical problems. The Cochrane Collaboration SRs are considered as the highest standard in evidence‐based health care resources. All SRs completed during the last 5 years (2013–2017) under the management of the Oral Health Group of the Cochrane Collaboration were identified. All primary trials included in the Oral Health Group SRs were identified and examined to establish their status regarding pre‐hoc approval of an independent ethics committee (EC), often termed Institutional Review Board (IRB) before commencing recruitment of trial participants. Ninety‐five SRs contained 960 primary trials, of which 272 (28.3%) were not examined by the author of this paper. Amongst the remaining 688 primary trials, 198 (29%) contained no reference to study conduct approval by a research ethics committee. The majority of primary studies referred to an EC/IRB approval with or without identifying the name of the ethics committee (n = 401, 58%), whereas some papers identified both the committee name and a protocol or reference number of the EC/IRB approval (n = 89, 13%). The Cochrane Collaboration, along with other developers of SRs, should adopt the policy established by COPE with regard to what to do if one suspect an ethical problem, that is, request evidence of EC/IRB approval. All stakeholders should rest assured that clinical policies and practices based on SRs are based on ethically sound clinical research.