Two size-groups of dorsal-spined, first-stage, nematode larvae were found in feces of woodland caribou, Rangifer tarandus caribou (Gmelin), in Alberta from [1976][1977][1978][1979][1980][1981][1982]. Larvae from caribou feces in northeastern Alberta were 451 ? 17 pm in length, while those from westcentral Alberta were 362 f 18 pm in length. Larvae collected from west-central Alberta developed to the infective stage, experimentally, in the terrestrial gastropod Triodopsis multilineata (Say) and were infective to captive mule deer fawns, Odocoileus h. hemfonus (Rafinesque). Adult nematodes, identified as Parelaphostrongylus odocoilei (Hobmaier and Hobmaier, 1934), were recovered from the skeletal muscles of the mule deer.