During the winter of 1977-78, investigations on the overwintering of adult mosquitoes were conducted I the southeastern region of Saskatchewan where the average daily minimum air temperature for January is - 20.4 C. Only Anopheles earlei (2 females) were recovered from 23 traps placed over mammalian burrows. Culex tarsalis (2 females), Cx restuans (1 female), Culiseta inornata (1 female) and An. earlei (2 females) were recovered from 17 traps placed over crevices and caverns located in rough stony embankments. Since all the mosquitoes are known summer-time hosts of western equine encephalomyelitis virus, an interest in their over-winter survival is partly related to their role in the natural history of the virus in Saskatchewan.