An Er(3+):Yb(3+):LuAl(3)(BO(3))(4) crystal doped with 24.1 at.% Yb(3+) and 1.1 at.% Er(3+) ions was grown by the flux method. The polarized spectroscopic properties related to the operation of 1.5-1.6 microm laser of the crystal were evaluated at room temperature. The laser properties of a 0.7-mm-thick, c-cut crystal were investigated in diode-end-pumped hemispherical and plano-plano cavities, respectively. Compared with those of Er(3+):Yb(3+):YAl(3)(BO(3))(4) crystal obtained under similar experimental conditions, higher maximum output peak power, higher slope efficiency, and lower threshold were achieved in the Er(3+):Yb(3+):LuAl(3)(BO(3))(4) crystal.