A list of nematode parasites found in rats from Guam in the Marianias Islands is presented. One sp. of the genus Rictularia is dealt with in particular since the male of this worm does not conform in morphology to Rictularia tani described from rats in China. The Guam females compare favorably with Rictularia tani. There does not appear to be enough evidence to establish a new sp. nor similarity in males to designate these worms from Guam as Rictularia tani. Before speciation can be secure more material, particularly males, from the Orient and Marianas Islands should be compared.