The longjaw cisco, Leucichthys alpenae, is shown to be a species new to the Lake Erie fauna. The taxonomic work on Lake Erie ciscoes is reviewed. Thirty three specimens of L. alpenae taken in 1946, 1947 and 1957 are compared morphometrically with Leucichthys artedi of Lake Erie, the only other cisco species in the lake. L. alpenae has a longer and deeper head, longer maxillary and fewer gill rakers. L. alpenae is more distinct from L. artedi in Lake Huron than in Lake Erie. The rate of growth of L. alpenae in Lake Erie compares favourably with that in Lake Michigan.