Erbium (Er 3+ ) doped ytterbium garnet Yb 3 Al 5−y Ga y O 12 (y=0, 0.55 and 1.1, YbAGG) thick films were grown by the isothermal liquid phase epitaxy method (LPE) on LuAG or YAG substrates. The influence of gallium on the photoluminescent properties of Er 3+ is presented in this paper. Room temperature transmission and emission spectra were measured for the 0.5at% Er 3+ :YbAGG films with a different doping level of Ga. Also Er 3+ :Yb 3 Al 3.9 Ga 1.1 O 12 (y=1.1) films with a different doping level of erbium (0.5, 1 and 2at%) were tested. The presence of gallium significantly affects the fine splitting and total intensity of erbium emission in an infrared region (the transition 4 I 13/2 → 4 I 15/2 ). Even at the highest doping level of erbium (2at%), no up-conversion luminescence was observed, resulting in a maximum efficiency of the infrared emission. The lifetime of luminescence at 1530nm was studied for all samples.