The bmi-1 gene was discovered as a clonal integration site of the Moloney murine leukaemia virus in B-cell lymphomas. The Bmi-1 protein contains the RING finger motif and is homologous to two Drosophila proteins known to be part of a multimeric protein complex involved in repressing gene transcription. A similar role for the highly conserved Bmi-1 protein in mammalian cells has been suggested. The coding regions for the mouse and human genes are known and are 92% homologous. This study involved PCR amplification, cloning, and sequencing of the 980bp feline bmi-1 coding region which was shown to be 92% and 97% homologous to the mouse and human genes respectively. From the open reading frame the feline protein is 326 amino acids in length and is 99% homologous to the human protein and 97% homologous to the mouse protein. This data is consistent with the closer relationship between the feline and human genomes and provides another experimental system in which to analyse Bmi-1 function.