Medical reports of Antarctic expedition teams indicate that health is affected under these extreme conditions. Beside the consequences of isolation and confinement on stress-dependent immune-modulation, environmental hypobaric hypoxia may additionally affect immunity. Therefore, this study at Concordia Station (Dome C, 3233m) seeks to investigate the early consequences of confinement and hypobaric hypoxia. 9 healthy male participants were included in this study. Data collection occurred ~2 months prior travelling to Antarctica (baseline), 1 week and 1 month upon arrival at Concordia. Parameters included basic physiological variables, psychological stress tests, cell blood count, stress hormones and markers of innate immune functions in resting and stimulated immune cells. In summary, living conditions at high altitude at Dome C influence the innate immune system´s response. As this early adaptation is not related to psychological stress, the changes observed are likely to be induced by environmental stressors, especially hypoxia. As hypoxia is triggering ATP catabolism to hereby increase endogenous adenosine concentrations, this and the increased catecholamine concentration might contribute to the early - reversible - down-regulation of innate immune functions.