Microbial ecology of some soils of the dry valleys of Victoria Land was investigated. The microorganisms in these polar deserts exist under some of the severest natural conditions. The soils are generally sandy, alkaline, and saline, with low organic matter, and they usually have low available moisture. The mesophilic bacterial count of these soils varied from several million per gram to no detectable bacteria. In general, the counts were very low in most typical desert soils, but in regions of glacial melt water where algae were present, a significant bacterial population was present. Various green and blue-green algae were detected in these soils. Fungi were detected infrequently as were actinomycetes. Many chromogenic bacteria were observed, and most isolates were gram-negative short rods. Various micrometerological, chemical, and physical parameters were measured and correlated with microbiological activity.