Cosmocerca leytensis sp. nov. (Ascaridida, Cosmocercidae) from the large intestine of Cyrtodactylus gubaot (Squamata: Gekkonidae) collected on Leyte Island, Philippines is described and illustrated. Cosmocerca leytensis sp. nov. is the 30th species assigned to the genus, the 4th from the Oriental region, and the first from the Philippine Islands. The new species is most similar to those species possessing 4 pairs of plectanes, i.e., C. archeyi, C. australis, C. oroensis, and C sardiniae. Cosmocerca sardiniae lacks lateral alae; C. archeyi, C. australis, C. leytensis sp. nov. and C. oroensis possess lateral alae. Spicule length of C. oroensis is less than 75 μm, while C. archeyi, C. australis, and C. leytensis sp. nov. have spicule lengths greater than 75 μm. Males of C. australis possess 2 pairs of rosette caudal papillae, which are lacking in C. archeyi and C. leytensis sp. nov. Females of C. archeyi posses a conical tail, females of C. leytensis sp. nov. have a rounded posterior end supporting a flexible filament.