Bacteriophage is a live micro-organism, a natural enemy of bacteria. Canadian microbiologist Felix d'Herelle proposed that bacteriophage might be applied to the control of bacterial diseases, however in the West this idea was not explored with the same enthusiasm as in the former Soviet Union and was eventually discarded with the arrival of antibiotics. Phage therapy is successfully used for the treatment of a wide spectrum of bacterial infections. Such experience has now become extremely important with the rapidly-increasing spread of antibiotic-resistant bacterial infections which are almost impossible to overcome these days. Phage therapy has been considered as an alternative to antibiotic-therapy and it is now attracting global interest. Most of the scientific works in phage therapy were published in Russian and are thus not easily available in the West. This fact inspired the authors to write a book based on the historical publications found in the library of the Eliava Institute.