Technical Abstract: Russian wheat aphid (RWA), Diuraphis noxia (Mordvilko), is a serious insect pest which causes severe economic losses in wheat (Triticum spp.). Among the various US RWA biotypes detected, biotype 1 (RWA1) and biotype 2 (RWA2) are the most prevalent and most virulent on many cultivated genotypes. Although many RWA resistant sources are available for these biotypes as landraces, genetic relatedness among such resistant sources should be characterized to most efficiently guide gene introgression strategies in breeding programs. In this study, 38 hexaploid accessions resistant to biotype 1 and/or biotype 2 were evaluated for their genetic diversity using the amplified fragment length polymorphism (AFLP) technique. Fifteen AFLP selective primer combinations were used to genotype these accessions, resulting in 893 amplicons. Of these, 274 (30.6%) informative polymorphic bands were used for genetic diversity analysis. Genetic similarity coefficients ranged from 0.47 to 0.87 among the resistant accessions, indicating high genetic diversity among them. Cluster analysis grouped the 38 accessions into two major clusters, I and II, including resistant lines for RWA1 and RWA2. The study indicated that accessions conferring RWA1 or RWA2 resistance comprise a diversified population to support introgression efforts and thereby will have the potential for future breeding studies for RWA resistance in wheat.