Alumina/zirconia-glass composites prepared by melt-infiltration were investigated to evaluate the influence of zirconia addition on mechanical and optical properties of the composites and glass penetration kinetics. The infiltration distance was parabolic with respect to time as described by the Washburn equation and the penetration rate constant, K, decreased due to the reduction In pore size as the amount of zirconia rose. The zirconia addition increased lightness ($L^*$) but reduced K, transmittance and color sharpness ($C^*$) It can be concluded that the zirconia addition was not effective to the mechanical properties of the composites due to the increase in porosity even though the toughness of the composites increased when zirconia was added up to 15 wt%.