We report the effects of electron irradiation on graphene Field Effect Transistor (FET) devices. We irradiated the graphene devices with 30keV electrons and measured the electrical transport properties in high vacuum in-situ. Upon electron irradiation, a Raman ‘D’ band appears. In addition, we observed that the doping behavior of the graphene devices changed from P to N type as a result of the irradiation. We also observed a shift of the Dirac point while the graphene FET device stays in vacuum and after it interacted with environmental molecules under ambient conditions.