The effects of the presence of Ga2O3 on low-temperature sintering and the phase stability of 4, 5, and 6mol% Sc2O3-doped tetragonal zirconia ceramics (4ScSZ, 5ScSZ, and 6ScSZ, respectively) were investigated. A series of zirconia sintered bodies with compositions (ZrO2)(0.99-x)(Sc2O3)(x)(Ga2O3)(0.01), x=0.04, 0.05, and 0.06 was fabricated by sintering at 1000 degrees C to 1500 degrees C for 1h using fine powders that were prepared via the combination of homogeneous precipitation method and hydrolysis technique using monoclinic zirconia sols synthesized through the forced hydrolysis of an aqueous solution of zirconium oxychloride at 100 degrees C for 168h. The presence of 1mol% Ga2O3 was effective in reducing sintering temperature necessary to fabricate dense bodies and enabled to obtain dense sintered bodies via sintering at 1100 degrees C for 1h. The phase stability, that is, low-temperature degradation behavior of the resultant zirconia ceramics was determined under hydrothermal condition. The zirconia ceramics codoped with 1mol% Ga2O3 and 6mol% Sc2O3 (1Ga6ScZ) fabricated via sintering at 1300 degrees C for 1h showed high phase stability without the appearance of monoclinic zirconia phase, that is the tetragonal-to-monoclinic phase transformation was not observed in the 1Ga6ScZ after treatment under hydrothermal condition at 150 degrees C for 30h.