As a result of the present revision only 40 species of Cryptophagus are recognized in North America, compared with 62 listed in the Leng Catalogue. The geographic distribution of these species is considered, and their probable status as endemic, Holarctic or introduced elements of the North American fauna is indicated. The taxonomy of the genus is discussed in general terms, and the reliability of the characters used in specific determination is evaluated. A dichotomous key to species, based largely on external morphological characters is provided, with synopses giving brief descriptions (with illustrations), comparative notes, notes on distribution and habitats (where known) and records by state or province. Five of the species are new: Crytophagus stromus, latens, nobilis, peregrinus, varus, and the following are recorded from North America for the first time: Cryptophagus obsoletus Reitter, fallax Balfour-Browne, scutellatus Newman, lycoperdi Scopoli, lapponicus Gyllenhal, scanicus Linnaeus, hexagonalis Tournier. The following new synonymy is also established: Cryptophagus acutangulus Gyllenhal (= prominens Casey, restrictus Casey), distinguendus Sturm (= keeni Casey), pilosus Gyllenhal (= parvinoda Casey, infuscatus Casey, plectrum Casey, cicatricosus Casey), quadrihamatus Mäklin (= plagiatus Poppius), corticinus Thomson (= depressulus Casey), dentatus Herbst (= quadridentatus Mannerheim), bidentatus Mäklin (= punctatissimus Mäklin), confertus Casey (= archangelicus J. Sahiberg), hebes Casey (= lyraticollis Casey, otiosus Casey), cellaris Scopoli ( = rupimontis Casey, angustatus Casey), laticollis Lucas ( = inscitus Casey, cribricollis Casey), setulosus Sturm ( = antennatus Casey, grossulus Casey), croceus Zimmermann (= fungicola Zimmermann, nodifer Casey, amputatus Casey, laticlavus Casey, densicollis Casey), tuberculosus Mäklin (= debilis LeConte, brevipilis Casey, lepidus Casey, boulderanus Casey, instabilis Bruce), difficilis Casey (= contractus Casey).