Three peculiarities distinguish the deepwater (68m) Lake Vanda in Antarctica: a relatively high temperature, increased salinity, and the presence of H2S are noted in its bottom layer. Saprophytic microorganisms in the lake water were found in amounts of only a few or, more rarely, dozens in 40ml of water. The total numberof bacteria ranged from 6,000 to 172,000 cells/ml. The highest figures, both on the total numbers of bacteria and on the saprophyte population, were determined in the intermediate layers, at 30 and 40-50m, respectively. The microbial strains isolated from the water and ooze belonged to the genera Pseudomonas, Chromobacterium, Bacillus, and Mycobacterium. Yeast organisms were also detected. Sulfate-reducing bacteria were detected in the lake ooze only at one station; thione bacteria were not found. Photosynthesizing bacteria were isolated from the ooze at all four stations.