The Russian wheat aphid, Diuraphis noxia (Mordvilko), probably from the Iranian–Turkestanian range, is a recently introduced pest that infests a major portion of the small grain belt of the U.S.A. Although fungal pathogens are important natural enemies of cereal aphids worldwide, their role in the regulation of Russian wheat aphid populations has received little attention, in or outside of North America. Nevertheless, pathogenic fungi (Beauveria bassiana, Verticillium lecanii and numerous Entomophthorales species) have been identified from Russian wheat aphid in several states of the United States and Canadian provinces. Data on these native natural enemies and the available damage reports indicate, however, that the fungal complex resident in North America is generally not well suited for Russian wheat aphid control. Although native fungi have some impact on D. noxia population levels, apparently they do not prevent economic damage to small grains. Although fungi appear to be ineffective in controlling the aphid in North America, in regions where D. noxia is indigenous (the semiarid mountain ranges of central Asia), economic damage is rare, suggesting that more effective natural enemies, possibly including fungi, may regulate the aphid populations in these areas. The pool of aphid pathogens in the United States, therefore, has been and is being expanded by importing exotic species or isolates. Although a number of promising fungal pathogens were collected in North America and during foreign exploration, to date only l exotic isolate, Zoophthora radicans, has been released against the aphid on this continent. Use and success of microbial methods of control of cereal aphids depend upon an accurate assessment of research results conducted over vast and diverse areas. This assessment should consider the limits of efficiency and long-term profit within which a given pathogen might be useful for the protection of the crop. This article reviews the current status of research on fungal pathogens for control of the Russian wheat aphid in the United States.