BACKGROUND: Despite the evidence showing the promise of HIV treatment as prevention (TasP) in reducing HIV incidence, a variety of ethical questions surrounding the implementation and "scaling up" of TasP have been articulated by a variety of stakeholders including scientists, community activists and government officials. Given the high profile and potential promise of TasP in combatting the global HIV epidemic, an explicit and transparent research priority-setting process is critical to inform ongoing ethical discussions pertaining to TasP. METHODS: We drew on the Arksey and O'Malley framework for conducting scoping review studies as well as systematic approaches to identifying empirical and theoretical gaps within ethical discussions pertaining to population-level intervention implementation and scale up. We searched the health science database PubMed to identify relevant peer-reviewed articles on ethical and implementation issues pertaining to TasP. We included English language articles that were published after 2009 (i.e., after the emergence of causal evidence within this field) by using search terms related to TasP. Given the tendency for much of the criticism and support of TasP to occur outside the peer-reviewed literature, we also included grey literature in order to provide a more exhaustive representation of how the ethical discussions pertaining to TasP have and are currently taking place. To identify the grey literature, we systematically searched a set of search engines, databases, and related webpages for keywords pertaining to TasP. RESULTS: Three dominant themes emerged in our analysis with respect to the ethical questions pertaining to TasP implementation and scale-up: (a) balancing individual- and population-level interests; (b) power relations within clinical practice and competing resource demands within health care systems; (c) effectiveness considerations and socio-structural contexts of HIV treatment experiences within broader implementation contexts. CONCLUSION: Ongoing research and normative deliberation is required in order to successfully and ethically scale-up TasP within the continuum of HIV care models. Based on the results of this scoping review, we identify several ethical and implementation dimensions that hold promise for informing the process of scaling up TasP and that could benefit from new research.