AbstractBased on a large number of specimens deposited in many collections, and on material collected in a sampling program in Yucatán Peninsula, Mexico, 19 North American species of Clistopyga Gravenhorst, 1829 (Hymenoptera: Ichneumonidae) are reported. Five species, C. aenigmatica, C. arizonica, C. juliana, C. maya, and C. oaxacana, are described as new. Clistopyga covarrubiasi Khalaim and Hernández, 2008 is synonymysed with C. recurva (Say, 1835) and C. sauberi Brauns, 1898 is once again re-synonymysed with C. canadensis Provancher, 1880. Data on diagnosis, variation, distribution, and hosts of all species are provided. All previously known species are re-described. The present revision extends the distributional range of the Neotropical species C. calixtoi Gauld, 1991, C. fernandezi Gauld, 1991, and C. henryi Gauld, Ugalde, and Hanson, 1998 to the southern part of the Nearctic Region (northern Mexico), and the area of the Nearctic species C. manni Cushman, 1922 to the northern part of the Neotropical region (southern Mexico). An illustrated identification key to all North American Clistopyga species is provided.