We assessed effects of vegetation and fire on small mammals in open vegetation formations of the Busanga Flood Plain (Kafue National Park, Zambia) in areas of low and high fire recurrence. The impact of fire was related further to the time elapsed between the last fire and the time of trapping (fire age). Sampling sites covered three management zones: intensive utilization (tourist areas), wild (less used), and wilderness (no road access). Vegetation type, fire recurrence, fire age, and management zone were independent variables. Communities were similar in grassland and on termitaria but differed from miombo. Species richness was highest on termitaria, followed by grassland and miombo. Species numbers declined with increasing fire frequency but were unaffected by fire age. In contrast, the average body mass of species occurring at any one site (only adult individuals considered) declined with the time elapsed between the time of capture and the last fire (the longer the time interval, the lower the body mass of species averaged over the species found at the site). This response implies higher vulnerability of the smaller species to fire and slower recolonization potential of smaller species after fire. The interactions between fire, vegetation characteristics, and small mammals need to be reviewed, given their importance in the functionality of this ecosystem.