The complete nucleotide sequence of a Thai isolate of Papaya ringspot virus (PRSV) type W (PRSV-W) was determined. The viral genome is 10,323 nucleotides (nts) long and contains an ORF encoding polyprotein 3,343 amino acids (aa) long, flanked with 5'- and 3'-non-coding regions (NCRs) of 85 and 206 nts, respectively. Out of the ten putative proteins P1 is the most variable (73.9% similarity) as compared to the PRSV type P (PRSV-P) sequences, while the CI protein is most conserved (99.1% similarity). The sequence similarity among the type W and P isolates also suggests that the P type arose from the W type. However, no significant difference between types P and W that would account for the host specificity was disclosed.