The Thai horseshoe bat (Rhinolophus siamensis), sometimes called the Thai leaf-nosed bat, is a species of bat from the family Rhinolophidae. It is frequently listed as a subspecies of the Big-eared horseshoe bat, but this may be a result of the two species being taken in sympatry in Laos. It is native to China, Laos, Thailand, and Vietnam.The species is listed as Least Concern on the IUCN Red List, as its extent of occurrence is much larger than 20, 000 km2, and there is little likeliness that its population is declining quickly enough to qualify for listing in a more threatened category.Little is known about the Thai horseshoe bat, including its abundance, population size, population trend, major threats, natural history, or presence in protected areas. It is assumed that the Thai horseshoe bat is associated with limestone caves in evergreen forests like other species in its genus.