The Megadermatidae is a family of insectivorous bats belonging to the suborder Yinpterochiroptera. Worldwide, the family currently comprises six extant species classified into six genera. In Thailand, three species across three gen-era: Megaderma, Lyroderma, and Eudiscoderma have been recorded. This study documents the specimens of the family Megadermatidae preserved in 70% ethanol at the Natural History Museum Thailand (THNHM). The examined col-lection, spanning from 1951 to 2023, represents all 77 prov-inces nationwide. All specimens were examined following THNHM permission and curation protocols. Examination of 156 non-type specimens revealed two species across two genera: Megaderma spasma (Linnaeus, 1758) with 132 spec-imens (85%) and Lyroderma lyra (Geoffroy Saint-Hilaire, 1810) with 24 specimens (15%). The distribution of the two genera varied: M. spasma was found in all regions, while L. lyra was restricted to only three regions (Central, Western, and Southern Thailand). This disparity suggests that the number of specimens preserved in museums can serve as an indicator of the distribution range for bats in the family Megadermatidae. However, this specimen data may not be sufficient to determine the complete or true distribution range of these two bat species in Thailand. Nevertheless, it provides an important database for identifying key historical and current habitats, which is valuable for future research.