The complete genome sequence of a new virus infecting yam plants exhibiting mosaic symptom in Brazil was determined. The genome of this virus is composed of two molecules of positive-sense RNAs of 5979 and 3809 nucleotides in length, excluding the poly(A) tails. One large open reading frame (ORF) in each genomic segment (RNA1-ORF1 and RNA2-ORF2) was predicted. The highest amino acid sequence similarity in the Pro-Pol core region of RNA1 and the CP region of RNA2 was observed with chocolate lily virus A (a putative member of the family Secoviridae), with 54.6 and 27.7 % identity, respectively. This virus is thus likely to be a new member of the family Secoviridae, and we propose the tentative name "dioscorea mosaic-associated virus" (DMaV) for this virus.