Actinobacillus pleuropneumoniae (APP) is the causative agent of porcine pleuropneumonia, a very contagious disease that implies a high cost to the industry yearly. To date, bacteriophage-related genes have been found in this bacterium, but no complete prophage genome capable of producing viral particles is known. Here, we present 13 APP isolates that harbour copies of a Mu-like bacteriophage, PluMu, which could be potentially active prophages. Heat and mitomycin C were tested to induce the production of viral particles as assessed by a PCR approach. Concentrated samples obtained from filtered bacterial culture supernatants were analysed by transmission electron microscopy, and several bacteriophage-like structures and an intact bacteriophage were found. The genomes of these APP Mu-like prophages are similar to that of bacteriophage Mu, and other recently described Mu-like bacteriophages, and they all are close in evolutionary distance. Analysis of the CRISPR-Cas system in the PluMu-infected isolates suggests that mutations in the Cas system genes may explain the differences seen in viral particle production between isolates. PluMu is the first bacteriophage described to infect APP, and it could have an impact on bacterial pathogenicity.