A comparative study of mobility and anxiety of subadult flat-headed and Tuva silver voles in an open field test has been performed using arenas 50 and 63 cm in diameter. It is found that individuals of both species demonstrate higher movement speed and cover longer distances, both on the periphery and in general, on the larger arena. Interspecies behavioral differences have been identified only in the arena 63 cm in diameter. Subadult flat-headed voles demonstrate higher mobility and lower anxiety in the test compared to Tuva silver voles. Hypotheses pertaining to specific features of the ecology of the two species reflected in their behavior are proposed.