BeAn 58058 virus (BAV) was isolated from an Oryzomis rodent in Brazil. BAV was shown to be antigenically related to another poxvirus also isolated in Brazil, the Cotia virus, but it remained ungrouped. Electron microscopy revealed that BAV has a typical poxvirus morphology. The Hind III DNA profile of BAV genome was similar with that of VV WR and Lister, but some differences in the profile were detected. We have also detected the presence of genes homologous to vaccinia virus (VV WR) genes in the genome of BAV. Genes related to vaccinia thymidine kinase (TK) gene and vaccinia growth factor (VGF) gene were found. The patterns of TK and VGF mRNA transcripts described for vaccinia virus infected cells were observed in BAV infected cells. Nucleotide sequence of BAV VGF homologous gene was similar to VV WR VGF sequences. This similarity was further seen when cross-hybridization of total genomes of BAV and VV was done. Polypeptide synthesis of BAV and vaccinia in infected cells also showed similar profiles. The genetic data was used to construct a phylogenetic tree where BAV and VV were placed at the same cluster. Based on our findings we propose that BAV is a vaccinia virus variant.