Ixodes uriae White, 1852 is a parasite of polar, subpolar and boreal seabirds of the northern and southern hemispheres (Cooley & Kohls, 1945, U. S. Nation. Inst. Hlth Bull. 184, 246 p.; Gregson, 1956, Can. Dep. Agr. Publ. 930, 92 p; Wilson, 1970, Pacif. Ins. Monogr. 23: 78–88; Clifford, Yunker, Easton & Keirans, 1970, J. Med. Ent. 7: 438–45). This note reports I. uriae from a River Otter (Lutra canadensis Schreber), apparently the first record of this tick species from a mammal host.