The prevalence and intensity of nematodes from the stomach and the prevalence of nematodes in the oral cavity were recorded in the frillneck lizard, Chlamydosaurus kingii, in Kakadu National Park (Australia) between 1991 and 1994, in order to determine whether or not a seasonal pattern was evident. Seven species were recorded; Strongyluris paronai, Skrjabinoptera goldmanae, Abbreviata, confusa, Abbreviata anomala, Physalopteroides filicauda, Kreisiella sp. and a species of Trichostrongyloidea. Only S. paronai showed a seasonal pattern. Only larval S. paronai occurred in stomach samples and larvae of this species occurred seasonally in the oral cavity of C. kingii, substantiating earlier findings that this genus migrates within the host. The occurrence of S. paronai in the oral cavity coincided with the highest prevalence and intensity of S. paronai in stomach samples. This shows a previously unrecorded aspect in the life cycle of this nematode species. Prevalence of S. paronai was positively correlated with ambient temperature which is highest in the months preceding the monsoonal rains, and coincides with an increase in field metabolic rate and general activity of the host.