The Hypocreales with over one thousand described species have been the repository for all light- to bright-colored, soft-textured, perithecial ascomycetes with a Nectria-type centrum. Rogerson (1970) published a key to the genera in the Hypocreales and accepted over 115 genera with 26 generic synonyms in the order. Since then, 58 genera have been added. For this study all available type specimens of the type species of genera classified in the Hypocreales were examined. Fifty six genera, including six newly described genera with 43 generic synonyms, are accepted in three families, Bionectriaceae fam, nov., Hypocreaceae and Nectriaceae, of the order. Although now considered either part of or closely related to the Hypocreales, neither the Niessliaceae nor the Clavicipitaceae are treated comprehensively in this study. Fourteen genera with two generic synonyms are included in the Niessliaceae and six genera with one generic synonym are placed in the Clavicipitaceae. The remaining 84 genera are excluded from the Hypocreales and redisposed in their appropriate family and order. Genera excluded from the Bionectriaceae, Hypocreaceae, and Nectriaceae are described and illustrated based on their type species. For 16 genera previously placed in the Hypocreales the type specimen was either not located or not sufficient to make a modern taxonomic evaluation of the type species. For each genus the type species and species not recently treated are fully described and documented. A key to species is presented unless a recent key to species in that genus is available. In the Bionectriaceae a new genus, Ochronectria, is introduced for Nectria calami. Nectriella minuta, N. rubricapitula, N. utahensis, Pronectria echinulata, P. pertusariicola, and Protocreopsis viridis are described as new species. The following new specific combinations are proposed: Dimerosporiella cephalosporii, D. gnarapiensis, D. leucorrhodina, D. oidioides, D. pipericola, and D. sensitiva; Hydropisphaera arenula, H. arenuloides, H. boothii, H. cyatheae, H. dolichospora, H. erubescens, H. gigantea, H. haematites, H. hypoxantha, H. leucotricha, H. macrarenula, H. multiloculata, H. multiseptata, H. nymaniana, H. pachyderma, and H. suffulta; Ijuhya peristomialis, I. chilensis, I. aquifolii, I. bambusina, I. corynespora, I. dentifera, I. dictyospora, I. leucocarpa, I. paraparilis, and I. parilis; Lasionectria sylvana and L. vulpina; Nectriella curtisii, N. dakotensis, and N. galii; Nectriopsis sasae and N. queletii; Ochronectria calami; Peethambara spirostriata and for its anamorph Didymostilbe echinofibrosa, Protocreopsis foliicola, P. freycinetiae, P. javanica, P. pertusa, P. pertusoides, and P. phormiicola; Stilbocrea gracilipes and S. impressa. Two new names, Nectriella crouanii for Nectria aurea P. & H. Crouan, and N. halonata for Charonectria umbelliferarum, are proposed. In the Nectriaceae five new genera are introduced: Albonectria for species related with Nectria rigidiuscula, Haematonectria for the Nectria haematococca complex, Lanatonectria for the Nectria flavolanata-group, Rubrinectria for a species previously known as Nectria olivacea, and Viridispora for teleomorphs of Penicillifer. Cosmospora dingleyae and C. obscura are described as new species. The following new specific combinations are proposed: Albonectria rigidiuscula, A. albosuccinea, and A. verrucosa; Corallomycetella repens and C. jatrophae; Cosmospora aurantiicola, C. biasolettiana, C. camelliae, C. chaetopsinae, C. chaetopsinae-catenulatae, C. chaetopsinae-penicillatae, C. chaetopsinae-polyblastiae, C. chlorina, C. consors, C. digitalicola, C. diminuta, C. diploa, C. episphaeria, C. flammea, C. flavoviridis, C. ganymede, C. geastroides, C. glabra, C. joca, C. jucundula, C. kurdica, C. lasiodiplodiae, C. leptosphaeriae, C. macrochaetopsinae, C. magnusiana, C. meliopsicola, C. metepisphaeria, C. nothepisphaeria, C. papilionacearum, C. peponum, C. pseudepisphaeria, C. pseudoflavoviridis, C. purtonii, C. rickii, C. rishbethii, C. rubrisetosa, C. sansevieriae, C. stilbellae, C. stilbosporae, C. thujana, C. triqua, C. tungurahuana, C. vilior, C. viliuscula, C. wegeliana, and C. xanthostroma; Haematonectria haematococca, H. illudens, H. ipomoeae, H. monilifera, and H. termitum; Lanatonectria flocculenta with anamorph Actinostilbe macalpinei, L. flavolanata, L. mammiformis with anamorph Actinostilbe mammiformis, and L. raripila; Neonectria coccinea and N. galligena; Rubrinectria olivacea; Viridispora penicilliferi, V. alata, V. diparietispora, and V. fragariae; Xenonectriella leptaleae, X. ornamentata, and X. streimannii. In the checklist, some genera are excluded from the families treated here and placed among 19 families in 12 orders of ascomycetes and one basidiomycetous genus. Two genera are uniloculate, discomycetous loculoascomycetes; some have true apothecia and belong in the Helotiales and Pezizales, or are lichenized Lecanorales. Many of these taxa are placed in the Diaporthales and Xylariales (Hyponectriaceae and Thyridiaceae). Genera having immersed ascomata are often difficult to place; they include Charonectria and Hyponectria, now placed in the Hyponectriaceae, Xylariales; and Cryptoleptosphaeria, Cryptonectriella and Schizoparme, now placed in the Diaporthales. Several genera are placed in the Niessliaceae and Clavicipitaceae of the Hypocreales. In this section a new species, Charonectria amabilis, is described, and the new combinations Thyridium ohiense, Charonectria sceptri, Cryptoleptosphaeria gracilis, Cryptonectriella geoglossi, and Thelocarpon citrum, are proposed.