Blast fishing has destroyed many coral reefs in Southeast Asia by creating large fields of dead coral rubble where new coral recruits settle but cannot survive and grow. Possible management responses include reef rehabilitation of damaged areas, and/or increased enforcement to protect still-living ones. Here we show that in Komodo National Park, Indonesia, rehabilitation by installing locally-quarried rocks on blasted rubble fields can be relatively low cost (∼US$4.80 per m2) and simple, but it is not economically viable at large scales. Although rehabilitation without enforcement is unlikely to be effective, we compared rehabilitation data (costs and coral growth over 8 years) and enforcement costs to conduct two economic analyses: cost-per-area calculations and a cost-effectiveness model over 7 years, and found that rehabilitation costs ∼70 and ∼5-times more, respectively, than marine patrols to enforce blast fishing bans. Hence, we recommend that marine protected area managers prioritize investment in achieving compliance with regulations above investment in rehabilitation to ensure that reefs continue to generate biodiversity and fisheries benefits and tourist revenues.