BACKGROUND: The 1984 Mexico City Policy is a U.S. federal policy that has prohibited foreign nongovernmental organizations that receive U.S. international family planning assistance from using their own, non-U.S. funds to provide, counsel on, or refer for abortion services as a method of family planning, or advocate for the liberalization of abortion laws- except in cases of rape, incest, and life endangerment. The policy became known as the global gag rule (GGR) due to its silencing effect on abortion advocacy. Historically, it has only been attached to family planning funding, until 2017 when a presidential memorandum expanded the policy to nearly all US$8.8 billion in global health foreign assistance. In light of the aforementioned expansion, this scoping review aimed to describe and map the impacts of the GGR on global health, which in turn would identify research and policy gaps. This is the first time that all of the existing literature on the policy's impact has been synthesized into one article and comprehensively reviewed. METHODS: The review utilized Arksey and Malley's five-stage methodological framework to conduct a scoping review. Fourteen peer-reviewed databases and 25 grey literature sources were searched for publications between January 1984 and October 2017. Organizations and individuals working on GGR research and impact were also contacted to access their works from the same time period. These publications reported on impacts of the global gag rule on 14 domains in global health. RESULTS: The searches yielded 1355 articles, of which 43 were included. Overall, 80% of the identified sources were qualitative. The misunderstanding, miscommunication, and chilling effect of the policy underpinned the GGR's impacts. The frequently reported impacts on family planning delivery systems (34 articles) and the loss of U.S. funding (21 articles) were often related. Sources reported on the impact of the GGR on HIV and AIDS programs, advocacy and coalition spaces, and maternal and child health. Only three studies (6.9%) quantified associations between the GGR and abortion rates, concluding that the policy does not decrease rates of abortion. DISCUSSION: The GGR's development and implementation was consistently associated with poor impacts on health systems' function and outcomes. More peer-reviewed and quantitative research measuring and monitoring the policy's impact on health outcomes are needed. More research and policy analysis exploring the GGR's development and its implementation on the ground will improve knowledge on GGR consequences, and potentially shape its reform.