Gamasid mites were collected from small mammals in the mountains of northernmost Sweden in autumn, winter/spring and summer. Laelaptidae and Liponyssidae were the most common families. Haemogamasidae comprised a rather small proportion of the material. Greatest infestation was recorded in early spring and in summer, when the number of mites per infested host was also highest. The mammal species were statistically different regarding the infestation and mean value of the mites. Microtus agrestis had most mites. Next came Clethrionomys rufocanus and last C. rutilus and Sorex araneus. Adult M. agrestis were more infested than the younger ones. Generally more males than females were infested. Laelaps clethrionomydis was most abundant on Clethrionomys but Laelaps hilaris and Hyperlaelaps arvalis on Microtus agrestis. Haemogamasus ni di f ormis did not show special preference for any host species. It is more common than Haemogamasus nidi in the present material. In Scandinavia, H. nidiformis becomes relatively more common with increasing latitude.