This book discusses numerous problems occurring in relation to microbiological quality of lactic acid cheese. Lactic acid cheese constitutes the source of various nutritive substances, which results in a possibility of allochthonous micro-flora to grow despite the presence of starter micro-flora. One of the issues discussed herein comprised the results of microbiological research depending on tvarog packing system. The influence of the packing system on surface micro-flora population was assessed. Moreover, the problem of growth of enterococci and LAB (Lactic Acid Bacteria) populations depending on stage of tvarog production as well as the packing system are also raised. The issue of interactions occurring among micro-organisms that re-infect tvarogs and the influence of these interactions on the growth of individual micro-organisms was also discussed. The author presents also the possibility to apply JMTPH computer program for assessment of the dynamics of changes of tvarog micro-organisms during product storage. Another chapter includes assessment of the influence of lactic acid bacteria on the behaviour of individual groups of micro-organisms occupying tvarog surface, depending on packaging hermetic properties. It was also very important to assess the safety of tvarogs in the context of a possibility of enterotoxin synthesis in conditions of various packing systems.