Convincing evidence for an Ellesmerian orogenic front has been found in the subsurface of the Mackenzie Delta-Tuktoyaktuk Peninsula area of the Canadian Northwest Territories. Reinterpretation of conventional industrial seismic profiles has fixed the timing of an orogenic event which produced compressional structures identified on the crustal reflection profiles collected across the Campbell Uplift near the Mackenzie Delta. In one location the reinterpreted profiles clearly show downlapping geometries at the base of, and faulting of, the Devonian Imperial Formation. These observations can be interpreted to indicate a Late Paleozoic highland to the north or northwest of Campbell Lake. Other seismic profiles along the Tuktoyaktuk Peninsula show a major angular unconformity between the Imperial and the overlying Mesozoic sediments. The structural relationship between the Paleozoic and Mesozoic thus implies that there is a front of a Late Paleozoic orogenic belt in the subsurface of the Tuktoyaktuk Peninsula. The structure of this feature is interpreted as a complex three-dimensional thrust front which resulted from convergence from the north or northwest during the Late Paleozoic, probably associated with the Ellesmerian orogeny.