The RecA protein is widely recognized to have an important role in homologous recombination, DNA rearrangement, repair, and replication. A fragment of Mycobacterium avium DNA and Mycobacterium paratuberculosis DNA containing RecA-like sequences was identified by hybridization with the Mycobacterium tuberculosis RecA gene. The fragments were isolated by cloning PstI digests of M. avium and M. paratuberculosis DNA into pBluescript II ±. Southern hybridization and sequence analysis revealed that the 5' terminus of the genes was well conserved across species of mycobacteria. However, Southern hybridization analysis using a specific probe to the 3' terminus of the M. avium and M. paratuberculosis genes suggests there are two copies of the 3' terminus in each of the respective genomes. This data is important in the understanding of DNA metabolism pathways in pathogenic mycobacteria.