Endohelminths of the endangered Socorro Island tree lizard, Urosaurus auriculatus, from Socorro Island, Revillagigedo Archipelago, Colima, Mexico, were identified from 12 museum specimens. Nine of 12 lizards (75%) were infected with 1 species of Cestoda, Oochoristica whitfieldi; 3 species of Nematoda, Parapharyngodon alvarengai, Spauligodon oxkutzcabiensis, Strongyluris similis; and 1 species of Acanthocephala (larval cystacanth). Seven lizards harbored 1 helminth species; 2 lizards harbored 2 helminth species. On average, there were 5.1 ± 3.9 SD (range 1–11) helminth individuals per infected host and 1.2 ± 0.4 SD (range 1–2) helminth species per infected host. Five new host records were recorded.