Sixty-three adult (>1 year) Svalbard reindeer (Rangifer tarandus platyrhynchus) from the Arctic island Spitsbergen were all parasitized by abomasal nematodes of the family Trichostrongylidae. Seven species of nematodes were recorded. Of these, Grosspiculaqia occidentalis was found only in reindeer from inner parts of Nordenskiold Land, and specimens of Marshallagia marshalli were also much more abundant in this area than at the coast. These two species are, primarily, parasites of bovids, and their local distribution coincides with that of muskoxen which were introduced to Spitsbergen in 1929. The reindeer parasites Ostertagia griihneri and Skrijabinagia arctica were about equally abundant in both the inland and coastal reindeer subpopulations. The results indicate that G. occidentalis and M. marshalli may have been introduced to Spitsbergen with bovids, most probably muskoxen, and that 0. griihneri and S. arctica may have spread from the reindeer into the muskoxen population.