The type collection of Recent mammals in the Division of Mammals, National Museum of Natural History, Smithsonian Institution, contains 612 specimens bearing names of 604 species-group taxa of Carnivora, Perissodactyla, Artiodactyla, and Cetacea as of May 2016. This catalog presents an annotated list of these holdings comprising 582 holotypes; 16 lectotypes, two of which are newly designated herein; 7 syntypes (15 specimens); and 1 neotype. Included are several specimens that should be in the collection but cannot be found or are now known to be in other collections and therefore are not in the database. Thirty-seven of the names are new since the last type catalog covering these orders, Arthur J. Poole and Viola S. Schantz’s 1942 “Catalog of the Type Specimens of Mammals in the United States National Museum, Including the Biological Surveys Collection” (Bulletin of the United States National Museum, 178). One of these, Lutra iowa Goldman, 1941, was transferred to the National Museum’s Paleobiology Department collection and is mentioned only briefly in this work. Orders and families are arranged systematically following D. E. Wilson and D. M. Reeder’s 2005 Mammal Species of the World: A Taxonomic and Geographic Reference, third edition, volume 1; within families, currently recognized genera are arranged alphabetically, and within each currently recognized genus, species and subspecies accounts are arranged alphabetically by original published name. Information in each account includes original name and abbreviated citation thereto, current name if other than original, citation for first use of current name combination for the taxon, type designation, U.S. National Museum catalog number(s), preparation, age and sex, date of collection and collector, original collector number, type locality, and remarks as appropriate. Digital photographs of each specimen will serve as a condition report and will be attached to each electronic specimen record. An addendum contains two accounts for holotypes added to the collection subsequent to the publication of the catalog for their taxa. Appendices tabulate summary data for all four of our recent type catalogs (Fisher and Ludwig, 2012, 2014, 2015, and this volume) and include authors of names, collectors of type specimens, countries, islands, and provinces or states in which type specimens were collected, numbers of new names per decade, and summary numbers for holotypes, lectotypes, syntypes, neotypes, and new taxa since the last type catalog (Poole and Schantz, 1942) covering the entire type collection.