A new virus resembling members in the genus Carlavirus was identified in an Out of Yesteryear rose (Rosa sp.) by high-throughput sequencing. The virus was discovered during the screening of a rose virus collection belonging to Foundation Plant Services (UC-Davis). The full genome of the virus is 8825 nt long, excluding a poly(A) tail, and includes six predicted genes coding for replicase, triple gene block, coat protein (CP), and nucleic acid binding protein. The closest relative of the putative virus is rose virus A (RVA; genus Carlavirus), with 75% and 78% aa sequence identity in the replicase and CP, respectively. The relationship with RVA and other carlaviruses was supported by phylogenetic analyses using replicase and CP sequences. Based on genome organization, sequence identity, and phylogenetic analysis, the virus found in the Out of Yesteryear plant represents a new member of the genus Carlavirus and is provisionally named "rose virus B" (RVB). Further testing by reverse transcription PCR confirmed the presence of RVB in the original source and seven additional rose selections from the same collection.