The Amazon region is an important region for biodiversity, and many new species are described for this region each year. However, the diversity of parasites infecting Amazonian reptiles is still poorly known, and there are few studies about how parasite communities of these hosts are structured. Our study was designed to elucidate the parasite community structure of Thecadactylus rapicauda, one of the largest species of gekkonid lizards in the world, and to discover the relative utility of size, sex, and body mass of Thecadactylus rapicauda as predictive factors of the abundance of helminth parasites. We analyzed 40 individuals of T. rapicauda, of which 34 had parasites (85% of prevalence), with 269 specimens allocated to 10 species. Body size of the host showed a positive influence on the abundance of helminths. Host sex is another important factor related to the abundance of nematodes: females were usually heavily infected. We conclude that T. rapicauda has a high richness of the helminth species and that most of the species found infecting this host were nematodes with a direct life cycle. Additionally, we found new helminth species, which should be described formally in the future.