The extreme environment of the Dry Valleys has opposing views on the microbial diversity present. Using molecular biological techniques, a detailed study was undertaken of the prokaryotic community present in desiccated Antarctic Dry Valley mineral soils. Mineral soils were collected from the regions in the Upper Wright Valley, the labyrinth and a vertical transect from the valley floor to a peak ... at 1450' height. Mineral soils were also collected from in the Miers Valley and a vertical transect from the valley floor to a peak at 2135' height. In addition, water and sediment samples were collected from Don Juan Pond (Wright Valley) and Bratina Island with conductivity measured in the all samples. All samples were analysed by 16S molecular phylogenetic methods coupled with denaturing gradient gel electrophoresis. In situ ATP analysis and moisture content was completed on mineral soil samples in the Wright Valley and Miers Valley. PCR based analysis of bacterial integron diversity and the isolation of psychrotolerant microbial strains was conducted on Miers Valley samples.