A survey of the braconid wasps on midwestern United States tallgrass prairies was conducted using malaise trapping on six sites forming an east-west transect through the prairie zone in Kansas, Missouri, and Illinois. A total of 924 specimens, representing 184 species, was recovered. Statistical analyses indicated that the asymptote of actual species richness had not yet been approached using this sampling regime. Nevertheless, this is the most complete survey yet available of prairie braconid wasps. Patterns of distinctness of the prairie fauna relative to that of other nearby plant communities are beginning to emerge.