Abstract Phage therapy (PT) is a unique method of treatment of bacterial infections using bacteriophages (phages)—viruses that specifically kill bacteria, including their antibiotic-resistant strains. Over the last decade a marked increase in interest in the therapeutic use of phages has been observed, which has resulted from a substantial rise in the prevalence of antibiotic resistance of bacteria, coupled with an inadequate number of new antibiotics. The first, and so far the only, center of PT in the European Union is the Phage Therapy Unit (PTU) established at the Ludwik Hirszfeld Institute of Immunology and Experimental Therapy, Wrocław, Poland in 2005. This center continues the rich tradition of PT in Poland, which dates from the early 1920s. The main objective of this chapter is to present a detailed retrospective analysis of the results of PT of 153 patients with a wide range of infections resistant to antibiotic therapy admitted for treatment at the PTU between January 2008 and December 2010. Analysis includes the evaluation of both the efficacy and the safety of PT. In general, data suggest that PT can provide good clinical results in a significant cohort of patients with otherwise untreatable chronic bacterial infections and is essentially well tolerated. In addition, the whole complex procedure employed to obtain and characterize therapeutic phage preparations, as well as ethical aspects of PT, is discussed.