Loxosceles rufescens (Dufour, 1820), the Mediterranean recluse spider, is a cosmopolitan species with toxic venom which can occasionally cause dermatological injuries in humans. Here, we report the finding of L. rufescens through intensive survey and exploration of six natural limestone caves in the western region of Thailand. These data provide the first direct evidence of L. rufescens living in large numbers in a natural habitat outside of their native Mediterranean range. Although the currently known distribution of L. rufescens in Thailand is quite narrow (the spiders were only found in one of the six caves explored), data on their biology and local habitat preferences are provided to better understand the colonization requirements of this species in the target area.