Background: All studies classified as research involving human participants require research ethics review. Most regulation and guidance on ethical oversight of research involving human participants was written for pharmacotherapy interventions. Interpretation of such guidance for cluster-randomized trials and stepped-wedge trials, which commonly evaluate complex non-therapeutic interventions such as knowledge translation, public health, or health service delivery interventions, can pose challenges to researchers and regulators. Current guidance: The Ottawa Statement on the Ethical Design and Conduct of Cluster-Randomized Trials provides guidance on the ethical oversight and consent procedures for cluster-randomized trials, and while not explicit, this includes stepped-wedge trials. Yet, stepped-wedge trials have unique characteristics that differentiate them from standard cluster-randomized trials. In particular, they can be used to evaluate knowledge translation interventions within the context of a routine health system rollout; they may have a non-randomized design; and the decision to implement the intervention is not always made by the researcher. Many stepped-wedge trials do not undergo ethical review and do not report trial registration. This suggests that those undertaking these studies and research ethics committees perceive them as non-research activities. Recommendations: Through an ethical analysis of two case studies, we argue that stepped-wedge trials, like parallel arm cluster trials, are systematic investigations designed to produce generalizable knowledge. We contend that stepped-wedge trials usually include human research participants, which may be patients, health care providers, or both. Stepped-wedge trials are therefore research involving human participants for the purpose of ethical review. Nevertheless, the use of a waiver or alteration of consent may be appropriate in many stepped-wedge trials due to the infeasibility of obtaining informed consent and the low-risk nature of the interventions. To ensure that traditional ethical principles such as respect for persons are upheld, these studies must undergo research ethics review.