The number of no-take marine protected areas (here referred to as no-take areas, NTAs) on coral reefs has increased considerably in recent decades. Coincident with accelerating degradation of coral reefs, expectations of the benefits that NTAs can provide for coastal societies and sustainability of marine ecosystems has grown. These include increasing abundance of reef organisms both inside and outside NTAs, protecting key ecosystem functions, and providing social and economic benefits through improved fisheries and tourism. However, there is a lack of convincing evidence for many of these expectations. This is the first attempt to synthesize all potential costs and benefits of coral reef NTAs and critically examine evidence of their impacts on both ecosystems and societies. NTAs with high compliance consistently increase the diversity, density and biomass of exploited reef fishes and certain groups of motile invertebrates within their boundaries and have benefits for reef-associated tourism. Some NTAs provide small increases in the abundance of corals and decreases in macroalgal cover. The effects of NTAs on genetic diversity and connectivity among meta-populations are variable or as yet unquantified. There is limited evidence of NTAs providing social benefits through increased fishery yields and tourism revenue. There are examples of both positive and negative effects on social well-being. Finally, sharks, marine megafauna and microbial communities showed few tangible benefits from NTAs. Substantial gaps in the science of coral reef NTAs remain, especially in their capacity to provide socioeconomic benefits. A crucial research priority is understanding how the cumulative effects of climate change will influence the various benefits that NTAs provide. To be effective, NTAs must be used in conjunction with a range of other management tools and applied according to local environmental and societal contexts.