Aims: To study the phenotypic and chemotaxonomic (i.e, phospholipid and cellular fatty acid composition) characteristics of environmental Aeromonas spp. and Vibrio spp. isolated from a drinking water reservoir near Vladivostok City, and the application of some chemotaxonomic markers for discrimination of the two genera and species. Methods and Results: Presumptive Aeromonas species were dominant in surface water samples (up to 25% of the total number of bacteria recovered). These strains were consistent with respect to the cultural and biochemical properties used to define the species Aeromonas sobria (seven strains) and Aer. popoffii (three strains). Vibrio mimicus (two strains) and Vibrio metschnikovii (one strain) were identified according to phenotypic features and cellular fatty acid composition. Conclusions: Environmental Aer. sobria isolates were atypical in their ability to grow at 42 degreesC, and were haemolytic, proteolytic and cytotoxic. Although it was present in a high proportion in the water samples, atypical Aer. sobria is not an indicator of polluted water. Significance and Impact of the Study: The incidence of Aeromonas in the drinking water reservoirs in the Far East of Russia is reported for the first time.