[en] Phages are viruses that infect bacteria in a very specific way. They are naturally present throughout the biosphere and are also involved in various biological processes in humans. The beginning of the twentieth century saw the birth of phage therapy which consisted of using phages to fight against bacterial infections. Very quickly, however, the medical community turned away in favour of antibiotics. In recent years, bacteria that are multi-resistant to antibiotics have appeared and are giving rise to renewed interest in phages in the face of this therapeutic impasse. This review aims to rediscover phage therapy in the medical profession, by detailing its mechanisms of action, its clinical aspects and its practical modalities of use in Belgium. Future challenges are also outlined.