The nucleotide (nt) sequences of the coat protein (CP) genes of two Japanese zucchini yellow mosaic virus (ZYMV) isolates (ZYMV-169 and ZYMV-M) were determined. The CP genes of both isolates were 837 nt long and encoded 279 amino acids (aa). The nt and deduced aa sequence similarities between the two isolates were 92% and 94.6%, respectively. The deduced aa sequences of CPs of the Japanese isolates were compared with those of previously reported ZYMV isolates by phylogenetic analysis. This comparison lead us to divide all ZMYV isolates into 3 groups in which ZYMV-169 formed its own distinct group.