To determine the natural distribution of entomopathogenic nematodes (Heterorhabditidae and Steinernematidae) in Oregon, 255 soil samples were taken from 59 sites representing ecologically diverse habitats and different geographic regions of the state. The presence or absence of entomopathogenic nematodes in samples was determined using theGalleria mellonella(L.) bioassay. Entomopathogenic nematodes were recovered from 30 soil samples representing 14 different sites. Twenty-four soil samples from 10 sites containedHeterorhabditisspp. and seven samples from five sites containedSteinernemaspp. We found significant association among geographic regions, habitats, soil textures, and genera of nematodes recovered. MoreHeterorhabditisspp. were recovered thanSteinernemaspp. at the high latitude of Oregon. Geographic region and soil texture may be the most important factors influencing the natural distribution of Heterorhabditis spp. in Oregon.