Exposure to hypoxic environments can have profound deteriorating effect on physiologic and cognitive abilities, this can be observed with decreased mood, impaired judgement and reduced reaction time. Recently, studies have reported that acute moderate exercise has a positive effect on cognition and mood in persons in normoxic conditions. Collectively, acute physiological changes resulting from moderate exercise may improve mood and cognition at altitude. PURPOSE: The purpose of this study was to determine differences in anxiety, fatigue and vigor when acute moderate exercise was performed in a normobaric hypoxic (NH) and normoxic (N) environment. To help quantify these changes, arterial oxygen saturation (SaO2), heart rate (HR) and blood pressure (BP) were also collected. METHODS: Nine (four women and five men) young, healthy participants completed a submaximal cycling protocol of four minute stages at 40, 80, and 120 watts. Following the submaximal protocol, a VO2 max test was completed to determine each participant’s cycling power that would elicit 60% of their max in subsequent visits. The VO2 max tests were completed in both (N) and hypoxia (NH). In both the N and NH conditions, baseline SaO2, HR, BP, anxiety, fatigue, and vigor values were collected and the participants spent 30 minutes acclimating before beginning exercise. The participant then cycled for 20 minutes and data was collected during the final 5 minutes of cycling. Data was collected again at 1, 15, 30, and 45 minutes after exercise. The order of conditions (N and NH) was counterbalanced. RESULTS: There was a main effect of condition, F (6) = 40.30, p = 0.000, time, F (1) = 284.08, p = 0.000, as well as an interaction between condition and time, F (6) = 20.81, p = 0.000, in SaO2. There was a main effect of time, F (6) = 51.02, p = 0.000, and an interaction, F (6) = 3.56, p = 0.005, in HR. Over time, SaO2 decreased and HR increased in the NH condition. There were no significant effects (P > 0.05) found for anxiety, fatigue, vigor, heart rate, and blood pressure. CONCLUSIONS: An acute bout of exercise has no effect on anxiety and fatigue in a hypoxic condition. However, an acute bout of exercise has a positive effect on vigor in NH. Future studies could examine the effect of graded exercise intensities and different exercise modalities on mood state in hypoxia.