Translucent Al2O3 ceramics were successfully produced by slip casting using a gypsum mold, provided that CaSO4 impurities, which had penetrated into the green bodies from the gypsum mold, were removed by the wash of HCl aqueous solution. Some of the calcined Al2O3 compacts were washed with HCl aqueous solution before sintering the compacts and the others were not washed with HCl aqueous solution. The relative densities of the sintered Al2O3 ceramics with HCl treatment were higher than those of the untreated samples. Grains in the HCl-treated samples, which sintered at 1350degreesC, grew homogeneously with about 1 mum in diameter. When the sintering temperature was higher, the grains grew homogeneously. The sintered Al2O3 ceramics with the HCl treatment were translucent. The transmittance value increased from 0 to 12% with increasing wavelength from 300 to 900 nm. The Al2O3 ceramics with the HCl treatment did not have the transmittance when the solid contents of slurry were low. The transmittance was influenced by the solid contents of slurry. On the other hand, grains in the HCl-untreated samples, which sintered at 1350degreesC, grew heterogeneously with the range from 0.2 to 2 mum. The Al2O3 ceramics did not have the transmittance.