Rhodococcus equi is a pathogenic member of the Actinobacteria responsible for causing serious infections in equines. A novel Siphoviridae bacteriophage (REQ1) lytic in R. equi was isolated and characterized. The genome size of REQ1 is 51,342 bp, and its sequence shares 7 % similarity to other DNA sequence in GenBank. Putative open reading frames were identified, and their functions were identified based on their predicted amino acid similarities. REQ1 phage has a modular genome, a feature common in double-stranded DNA phages.