The spread of introduced saltcedar (Tamarix spp.) throughout many riparian systems across the western United States motivated the introduction of saltcedar leaf beetles (Diorhabda carinulata, D. elongata; Chrysomelidae) as a biological control agent specific to saltcedar. I monitored small mammal populations for up to 12 years as saltcedar defoliation progressed at 3 of the original saltcedar beetle release sites and at an additional site where beetles established through dispersal. There was no evidence of any linear effect of increasing defoliation over time on small mammal species richness. Estimated population sizes of 4 small mammal species, based on mark-release-recapture trapping, showed linear responses to saltcedar defoliation at particular sites, but all of these species were represented by only 3 years of data at those sites. Increases in the abundance of 2 species of desert-adapted heteromyid rodents, Merriam's kangaroo rat (Dipodomys merriami) and Panamint kangaroo rat (D. panamintinus), may have occurred due to increasing habitat desertification associated with saltcedar biocontrol. Overall, however, results imply that saltcedar biological control is likely to have negligible effects on resident small mammal populations.