We studied small mammals in planted smooth brome (Bromus inermis) fields on Konza Prairie to assess the small mammal community associated with these frequently occurring anthropogenic grasslands in eastern Kansas. Also, we wanted to understand the impacts of land use changes resulting from this type of anthropogenic change as compared to native habitats. Relative to this latter interest, we compared the small mammal community in brome fields to that found in native tallgrass prairie, also on Konza Prairie, for the same years and seasons during the early to mid-1980s. Small mammals were trapped in brome (n = 2 study sites) and native tallgrass prairie (n = 14) in autumn (6 years), spring (5) and summer (4) during 1981–1986. Overall, 173 and 1893 individuals of rodents and shrews were captured in brome and native prairie, respectively. Across all seasons, community abundance in brome was greater in autumn than in spring and summer. Patterns of community abundance among seasons in brome were not proportionally similar to those found in tallgrass prairie. Although proportions in autumn were similar, the patterns in spring and summer were in contrasting directions; spring was higher in brome and summer was higher in prairie. When all seasons were combined, no effect on community abundance was observed from burning the brome fields. Community abundance in brome was similar on burned and unburned traplines in autumn and spring but not in summer. In summer, greater abundance of small mammals occurred on burned than on unburned research sites. The proportion of small mammals in burned brome fields in the three seasons mirrored the proportions observed on burned sites in native prairie. In contrast, these proportions were not similar for spring and summer in brome and prairie for unburned study sites. Species composition and the numerical dominance of species varied greatly between brome fields and native prairie overall as well as among seasons. Prairie voles (Microtus ochrogaster) were numerically dominant in brome fields, whereas deer mice (Peromyscus maniculatus) were in native prairie. Furthermore, herbivorous rodents were numerically dominant in brome fields, whereas seed-eating omnivores were the predominant species in native prairie. Finally, our study indicates that agricultural land use change can result in temporally and spatially variable small mammal communities that do not mirror those found in native tallgrass prairie.