Arthropod pests in forest and agricultural systems are affected by many pathogenic organisms. Among them, entomopathogenic fungi are the one most common control agents that regulate their populations. This review compiles the information available from Argentina and Brazil about the entomopathogenic fungi occurring in agricultural and natural environments. The scientific names of the fungi are listed according to the latest phylogenetically based classification of fungi. We present an updated list of arthropod-pathogenic fungi occurring in 15 of the 23 provinces of Argentina and 20 of the 27 states of Brazil based on published literature and our personal observations. The list includes a total of 114 fungal species from 53 genera: of Blastocladiomycetes (2 genera), Entomophthorales (8 genera), Harpellales (13 genera), and a diverse assortment of ascomycetes (primarily from Hypocreales) in 22 anamorphic and 5 teleomorphic genera. In the both countries, molecular studies on arthropod-pathogenic fungi are still in their early stages and have focused primarily on intraspecific variability and adequate generic assignment. This listing seeks to encourage more active collection and characterization of these fungi by both traditional and molecular approaches from the obviously rich but underexplored flora of fungi affecting arthropods throughout this large region of South America.