Cosmocercoides malayensis sp. nov. (Nematoda, Cosmocercidae) from the large intestine of Gonocephalus liogaster (Squamata, Agamidae) from Peninsular Malaysia is described and illustrated. Cosmocercoides malayensis sp. nov. represents the 23rd species assigned to the genus and the 10th species from the Oriental biogeographical region. Cosmocercoides malayensis sp. nov. differs from the previously described Oriental species in number and position of rosette papillae; however, it is most similar to C. bufonis and C. rickae in that these 3 species have 6 post cloacal rosette papillae. Cosmocercoides bufonis possesses a prebulbar copular swelling, which is absent in C. malayensis; C. rickae posssesess somatic papillae, which are absent in C. malayensis. Three addtional nematode species were found, adult specimens of Meteterakis singaporensis and Orneoascaris sandoshami and larva of Physocephalus sp.