The microstructural and high-temperature mechanical characteristics of conventionally sintered Al2O3-Y3Al 5O12-ZrO2 polycrystals with the ternary eutectic composition have been investigated. An equiaxed and fine-grained microstructure was obtained after the sintering of commercial powders of Al 2O3, Y2O3 and ZrO2 at 1500 °C for 10 h in air. The mechanical behavior was assessed by compression testing at constant strain rate and at constant load in air at temperatures between 1200 and 1400 °C. A brittle to ductile transition was observed with increasing temperature. Grain boundary sliding is the primary deformation mechanism in the ductile regime, as found in fine-grained superplastic metals and ceramics.