Tularemia is a bacterial zoonosis caused by Francisella tularensis. We conducted a serosurvey of black-tailed prairie dogs (Cynomys ludovicianus) in Devils Tower National Monument, Wyoming, US, following an epizootic in voles ( Microtus spp.) due to F. tularensis. Only 1 of 44 (2%) sampled prairie dogs was seropositive for F. tularensis, providing evidence of survival and potentially limited spread among free-ranging prairie dogs.