Five biotypes of the Russian wheat aphid (RWA1 to RWA5) have recently been identified based on the damage response of resistance genes (DN1 to DN9) in wheat. The response of two primary sources of Russian wheat aphid resistance in wheat, STARS 9301B and STARS 9577B, and susceptible barley cultivars to the new Russian wheat aphid biotypes was investigated. These barley entries showed differnial chlorosis and plant stunting damage responses to the Russian wheat aphid biotypes, indicating that these biotypes have unique virulence patterns in barely as well as wheat.