The Athabasca Oil Sands are located within the Western Canadian Sedimentary Basin, which covers over 140,200 km(2) of land in Alberta, Canada. The oil sands provide a unique environment for bacteria as a result of the stressors of low water availability and high hydrocarbon concentrations. Understanding the mechanisms bacteria use to tolerate these stresses may aid in our understanding of how hydrocarbon degradation has occurred over geological time, and how these processes and related tolerance mechanisms may be used in biotechnology applications such as microbial enhanced oil recovery (MEOR). The majority of research has focused on microbiology processes in oil reservoirs and oilfields; as such there is a paucity of information specific to oil sands. By studying microbial processes in oil sands there is the potential to use microbes in MEOR applications. This article reviews the microbiology of the Athabasca Oil Sands and the mechanisms bacteria use to tolerate low water and high hydrocarbon availability in oil reservoirs and oilfields, and potential applications in MEOR.