The influence of thermal treatment (TT) and irradiation by γ-quanta ( 60 Co, 1.25MeV) in the range of absorbed doses 106–108R on the absorption, luminescence and light yield (LY) of scintillators based on Lu3Al5O12:Ce (LuAG:Ce) single crystalline films (SCF) grown by LPE from the Pb-based flux is studied. It has been shown that transformation of the Fe3+↔Fe2+ and Pb2+↔Pb4+ valent states of iron and lead trace impurities cause the change in the optical absorption of SCF induced by the TT in air and vacuum in the range of annealing temperatures of 800–1200∘C. Possible types of radiation defects in LuAG:Ce SCF induced by γ-radiation are analyzed.