Tula virus (TUL) is a recently detected hantavirus carried by European common voles. Reverse transcriptase PCR cloning was used to study TUL S segment/N protein quasispecies. Both the distribution and character of mutations observed in three mutant spectra indicated limited selection at the protein level. At least 8% of the mutations were neutral or well tolerated; fixation of such mutations may play a role in TUL evolution in its natural host.