Nucleic acid sequence comparison between the Egyptian strain (Gl19) and the American strain (ND 18) of Barley Stripe Mosaic virus (BSMV) revealed a high degree of sequence similarity of γ RNAs comparing to ß RNAs of both strains. On the Other hand, nucleotide, and amino acid sequences of the two strains revealed differences in the 5' untranslated region (UTR) between the coat protein and êžµb gene. It was clear that five bases, and 18 out of 1 16 amino acids were found different. three amino acids insertion, and one amino acid deletion. Little differences were also observed regarding the 5' UTR of RNA γa as six nucleotides were changed. 12 out of 162 amino acids were differed and one amino acid deletion. Gl19 strain cross reacted specifically with the monoclonal antiserum raised against the coat protein of ND18 stain and the two coat proteins were indistinguishable in their sizes.