We have tested if a part of nuclear gene GSPT2 encoding N and M domains of translation termination factor eRF3b could be applied as a new molecular marker, using order Rodentia as a model group. The proposed fragment cannot be used as a phylogenetic marker at intrageneric level because of low variability within families and impossibility to resolve relationships in family Cricetidae. However, this part of GSPT2 gene allows to divide higher taxa reliably. Phylogenetic relationships between families established using the proposed molecular marker mainly correspond with contemporary conceptions. The new marker indicates close relationship of genus Acomys with family Gerbillidae in agreement with other molecular data but opposing to morphological ones. Thus the part of gene GSPT2 encoding N and M domains of eRF3b protein can be applied as an adequate phylogenetic marker in placental mammals at family and higher taxonomic levels. Also it can be used while solving controversial questions of phylogeny and taxonomy.