Introduction: Since obesity and overweight have dramatically increased in recent years, the purpose of this study was to compare the effects of hypoxia on responses of PYY3-36 and the appetite to interval exercise among overweight individuals. Materials and Methods: Eight healthy male subjects (age, 22.14±2.11 yrs; height,175.28±7.69 cm; weight, 87.03±5.95 kg; BMI, 28.4±1.5 kg/m2) voluntarily participated in the study and performed an exercise protocols (cycling) in noromxic and hypoxic conditions on two separate sessions (Counterbalance) with a one week interval. Interval exercise included 5 repetitions of 4-min activity at 85%of HRmax, followed by 2-min active restat 50% of HRmax. The environmental and training conditions were kept constant in two sessions, with the exception that the interval exercise was performed with 15% reduction in oxygen partial pressure in a hypoxic trial. Blood samples were taken before and after exercise (10, 20, 40, 60 and 80 minutes) and were analyzed for measuring the PYY3-36 using the ELISA technique. Results: Environmental conditions did not induce significant effect on PYY3-36 responses to interval exercise (P=0.1), though, exercise increased the PYY3-36, especially in normoxic conditions. In addition, although there was a reduction in the appetite following the two trials, environmental conditions had no significant effect on appetite (p=0.872). Conclusion: Interval exercises increase circulating levels of PYY3-36 and reduce appetite, irrespective of the environmental conditions (normoxia or hypoxia) in which the exercise is performed.