Euryoryzomys russatus, also known as the russet oryzomys, russet rice rat, or big-headed rice rat, is a species of rodent in the genus Euryoryzomys of family Cricetidae. It is a member of the genus Euryoryzomys, which was split off from Oryzomys in 2006. It is found in southern Brazil, eastern Paraguay and northeastern Argentina.