General observations are reported on helminth parasitism in Alaska. Cestodes are the most abundantly represented group, and many of the arctic-nesting birds are infected on the breeding grounds. Certain Eurasian spp. (Paranoplocephala omphalodes, Hymenolepis horrida and Helimosomum costellatum) have been recorded from Alaskan microtine rodents. This is thought to have zoogeographical implications of unusual interest. Trematodes are generally uncommon in Alaska, and host spp. ordinarily harboring these parasites farther south are not found infected in Alaska. Nematodes are numerically abundant, but appear restricted in numbers of genera and spp. The arctic climate does not appear to affect helminths adversely. Certain spp. (Paranoplocephala infrequens and Andrya primordialis) occur from the arctic regions south into the central U. S. Others (Syphacia obvelata and Andrya macrocephala) range from the Arctic to as far south as Mexico City. The occurrence of trichinosis in marine mammals offers an unusual problem in arctic helmir.thology. The problems concerned with host specificity of cestodes of the genus Diphyllobothrium must be elucidated before their epizootiology can be properly understood and control measures instituted. The common occurrence of Echinococcus granulosus in Alaska offers an important public health problem and important questions of an immunological nature. The undisturbed biotic conditions existing in Alaska contribute much to the success of this type of research.