This study investigates the accumulation of microplastics (MPs) in terrestrial wildlife, including vertebrates and tadpoles, in western Thailand, both inside and outside protected areas (PAs). A total of 136 individuals from 48 vertebrate species were examined, with snakes, tadpoles, birds, and amphibians being the most common. The average number of MPs per individual was 3.25 ± 3.63, and per body weight was 0.05 ± 0.08 MPs. Fibers were the most common type of MPs (77%), followed by fragments (22.22%). The quantities of MPs varied significantly among animal groups and between specimens collected inside and outside PAs. The study highlights the prevalence of plastic pollution in terrestrial vertebrates within Thai PAs and suggests that snakes, obtained from road kills, could serve as non-invasive indicators of plastic pollution. The findings emphasize the need for standardized solid waste management and conservation education to address the threat of plastic pollution to biodiversity in terrestrial ecosystems.This study investigates the accumulation of microplastics (MPs) in terrestrial wildlife, including vertebrates and tadpoles, in western Thailand, both inside and outside protected areas (PAs). A total of 136 individuals from 48 vertebrate species were examined, with snakes, tadpoles, birds, and amphibians being the most common. The average number of MPs per individual was 3.25 ± 3.63, and per body weight was 0.05 ± 0.08 MPs. Fibers were the most common type of MPs (77%), followed by fragments (22.22%). The quantities of MPs varied significantly among animal groups and between specimens collected inside and outside PAs. The study highlights the prevalence of plastic pollution in terrestrial vertebrates within Thai PAs and suggests that snakes, obtained from road kills, could serve as non-invasive indicators of plastic pollution. The findings emphasize the need for standardized solid waste management and conservation education to address the threat of plastic pollution to biodiversity in terrestrial ecosystems.