The complete genomic sequence of Habenaria mosaic virus (HaMV), which infects terrestrial orchids (Habenaria radiata), has been determined. The genome is composed of 9,499 nucleotides excluding the 3'-terminal poly(A) tail, encoding a large polyprotein of 3,054 amino acids with the genomic features typical of a potyvirus. Putative proteolytic cleavage sites were identified by sequence comparison to those of known potyviruses. The HaMV polyprotein showed 58 % amino acid sequence identity to that encoded by the most closely related potyvirus, tobacco vein banding mosaic virus. Phylogenetic analysis of the polyprotein amino acid sequence and its coding sequences confirmed that HaMV formed a cluster with the chilli veinal mottle virus group, most of which infect solanaceous plants. These results suggest that HaMV is a distinct member of the genus Potyvirus.