Single crystals of LuAG:Ce, LuAG:Pr and un-doped LuAG were grown by the vertical Bridgman method and studied for radiation hardness under gamma-rays with doses in the range 10–10 5 Gy ( 60 Co). A wide absorption band peaking at around 600nm springs up in all three types of crystals after the irradiations. The second band peaking at around 375nm appears in both LuAG:Pr and un-doped LuAG. Compositional variations have been done to reveal the spectral behavior of induced color centers in more detail and to understand their origin. Similarities in behavior of Yb 2+ centers in as-grown garnets are found, indicating that radiation induced color centers can be associated with residual trace amounts of Yb present in the raw materials. Un-doped LuAG and LuAG:Ce demonstrate moderate radiation hardness (the induced absorption coefficients being equal to 0.05–0.08cm −1 for accumulated doses of 10 3 –10 4 Gy), while LuAG:Pr is less radiation hard. The ways to improve the radiation hardness are discussed.