Abstract: Gyne (holotype), worker and male of Leptothorax athabasca sp.n. are described from the Athabasca River valley,Jasper National Park, Alberta, Canada. The most characteristic features of gyne and worker are a sharp dorsal crest ofthe petiolar node, a straight dorsal profile of the mesosoma, acute and straight horizontal propodeal spines, and a comparatively flat dorsal surface of the mesosoma. Leptothorax athabasca sp.n. has been found in only one very small plot ofa few 100 square meters, upriver of Athabasca Falls south of Jasper. It appears to be a rare, local species with adaptations to dwelling rock crevices. Possible reasons for such a restricted range are discussed. The new species nests inrock crevices, an exception among its congeners which usually are found in dead wood.