The isothermal shrinkage behaviors of fine zirconia powders (containing 2.8-2.9 mol% Y2O3) with specific surface areas of about 6 and 16 m(2)/g were investigated to clarify the effect of specific surface area on the initial sintering stage. The shrinkage of powder compact was measured under constant temperatures in the range of 1000 degrees-1100 degrees C. The increase in specific surface area enhanced the densification rate with increasing temperature. The values of activation energy (Q) and frequency-factor term (beta(0)) of diffusion at initial sintering were estimated by applying the sintering-rate equation to the isothermal shrinkage data. The Q of diffusion changes little but the beta(0) increases with the increase in specific surface area. It is therefore concluded that the increase in the specific surface area of fine zirconia powder enhances the shrinkage rate because of an increase in the beta(0) at the initial stage of sintering.