Until recently the conservation status of seven of the nine species of tarsier on the IUCN Red List was Data Deficient, and determining the status of these species has been a priority. In addition, there are believed to be numerous cryptic tarsier taxa. Tarsiers have been proposed as flagship species to promote conservation in the biogeographical region that includes Sulawesi and surrounding island chains. Therefore, identifying and naming cryptic tarsier species and determining their conservation status is not only a priority for tarsier conservation but also for regional biodiversity conservation. Two tarsier species, Tarsius sangirensis from Sangihe Island and Tarsius tumpara from Siau Island, occur within the Sangihe Islands, a volcanic arc stretching c. 200 km north from the northern tip of Sulawesi. The geographical information system database from The Nature Conservancy's Sulawesi Ecoregional Conservation Assessment was used in conjunction with field surveys to determine the conservation status of these two species. Our results show that both species are at risk from a small extent of occurrence and area of occupancy, small population size, high risk of volcanism, high human population density, fragmented populations (many of which are in marginal habitat), and lack of conservation areas for either species. In addition, there are no available ex situ conservation options. The Siau population is further threatened by hunting for bushmeat. Our recommendations are that T. sangirensis be categorized as Endangered and T. tumpara, which was included on the 2006–2008 list of the world's top 25 most endangered primates, as Critically Endangered on the IUCN Red List.