Bacteriophages are viruses, which exclusively infect bacteria. Bacteriophage therapy has a great potential in the treatment of pan- or multidrug resistant bacterial infections as argued in this review, and promising results have been published within recent years. The effects of the treatment are, however, still not fully understood and remain to be clarified. Furthermore, the facilities to produce legally approved bacteriophage products for human treatment must be available before the treatment becomes available to Danish patients.