Infectious diseases of upper respiratory tract (URT) represent serious problem for marine mammals adapted to noogenic conditions. Anthropogenic contamination of pool water is considered as an important source of potentially harmful bacteria. The changes in climatic conditions, nutrition and stress of animals living in an artificial environment can result in bacterial overgrowth and disease development with possible spread in the community. Treatment of already advanced disease is complicated and positive outcome largely depends on timely diagnostics. Regular control of behavioral and nutritional changes of marine animals and testing of exhaled airflow detect the early signs of an URT infection. The identification of etiologic agent is crucial to set up efficient treatment regimen based on selection of proper antibiotics or other antimicrobials. The results of the studies on the Black Sea marine mammal?s respiratory microflora conducted in the Batumi dolphinarium during 2012- 2017 have been analysed in parallel with the results of the monitoring of water microbial quality in the dolphinarium?s pool. It was shown that the URT microflora of healthy dolphins was considerably low in numbers (10- 200 cells per sample) but quite diverse. In animals with disease symptoms URT samples yielded > 1000 cells with reduced species diversity. No correlation of the water microbial data with the results of bacteriological investigation of the exhaled air was shown. The URT microflora of dolphins in Batumi dolphinarium was represented mainlly by Staphylococcus spp., Pseudomonas spp. and other non-fermenting G-bacilli, enterobacteria etc. Majority of these bacteria are considered as opportunistic pathogens capable to cause respiratory disease in the animals with weakened immune system. Among the bacterial isolates collected during 3 described cases of dolphin?s sickness in 2012 the species with high pathogenic potential for dolphins - Aeromonas salmonicida, Erysipelotrix ruthiopathie and Shewanella putrifaciens were presumptively identified along with opportunistic bacteria - S. aureus, S. epidermidis and Corynebacterium spp.