A study of the specific composition of Black Sea bottlenose dolphin (Tursiops truncatus) microflora at different periods of adaptation to captive conditions represents an important problem not previously investigated. Specific microbial associations in animals and humans are directly dependent on the physiological state of the host. When adapting to captive conditions, marine mammals are subjected to the influence of many unfavorable factors, including high microbial pollution in a novel anthropogenic environment. In addition, the specific composition of this microflora differs drastically from the bottlenose dolphin's natural microbial environment. By understanding the microfloral changes of animals adapting to captivity, we may determine the status of their adaptation and, hence, interpret the causes of disease and death of dolphins attributed to bacterial infections during adaptation. A complicating factor is the ongoing pollution of world ocean waters by industrial, agricultural and urban runoff, which leads to an increased microbial pollution index of the natural environment of wild marine mammals. This study of the delphinid adaptation process to novel microflora in captivity provides data that may serve as a model of the analogical adaptation process in wild populations of animals under deteriorating environmental conditions. The study was conducted at the Microbiological and Immunological Department of K.I. Scryabin MSAVMB and Utrish Marine Station of A.N. Severtsov IEEP RAS during 2000-2002. Black Sea bottlenose dolphins of different ages and sexes, and at various stages of adaptation to captivity, were the objects of investigation. The goal of our work was to study the dynamics of specific and quantitative changes of bottlenose dolphin microflora at various stages of adaptation to captivity. We isolated and identified 22 genera and 17 species of microorganisms. Bacterial species composition and percentages varied consistently in animals at different stages of adaptation to captivity, subject to modifications based on the physiological state of individual dolphins.