The complete nucleotide sequence of the RNA genome of bean yellow mosaic potyvirus (BYMV) has been determined. The RNA genome of BYMV is 9532 nucleotides long excluding the poly (A) tract. The RNA contains one open reading frame (ORF) of 9171 nucleotides encoding a large polypeptide of 3056 amino acids with a calculated Mr of 347, 571. Nine putative proteolytic cleavage sites, one by P1 protease, one by HC protease and seven by NIa protease, are identified by comparison with those identified for other sequenced potyviruses. The genetic organization of BYMV genome is proposed to be 5'UTR (190nt)-P1 (33K)/HC-Pro (52K)/P3 (41K)/6K1/CI (71K)/6K2/NIa-VPg (22K)/NIa-Pro (27K)/NIb (59K)/CP (31K)-3'UTR (171nt)-poly (A). Comparing the amino acid sequences of individual BYMV proteins with the corresponding proteins of other potyviruses, the BYMV proteins, excepting P1, have a high or moderate homology.