A moderately rich fauna of graptolites, comprising species dominated by Monograptus (sensu stricto), Retiolites, Stomatograptus, and Cyrtograptus is documented from Prairie Creek, southern Mackenzie Mountains, Northwest Territories. Graptolites of the upper Llandovery Monograptus turriculatus, Monograptus spiralis, and Cyrtograptus sakmaricus zones and of the Wenlock "unnamed zone" and Cyrtograptus rigidus and Monograptus testis – Cyrtograptus lundgreni zones are recognized. The species composition of these zones is significantly different from corresponding zones elsewhere in the Canadian Cordillera.Twenty-six species are described and illustrated, and of these, two are new: Stomatograptus canadensis and Cyrtograptus preclarus; and two species, Monograptus aff. riccartonensis and Cyrtograptus aff. sakmaricus might also be new. Several species, particularly Monograptus praecedens, Monograptus veles, and Monograptus cf. mutuliferus strigosus have not been prevously reported in North America.