Ultrafine beta -SiC powders mixed with 7 wt% Al2O3, 2 wt% Y2O3, and 1.785 wt% CaCO3 were hot-pressed and subsequently annealed in either the absence or the presence of applied pressure. Because the beta -SiC to (beta -SiC phase transformation is dependent on annealing conditions, the novel processing technique of annealing under pressure can control this phase transformation, and, hence, the microstructures and mechanical properties of fine-grained liquid-phase-sintered SiC ceramics. In comparison to annealing without pressure, the application of pressure during annealing greatly suppressed the phase transformation from beta -SiC to alpha -SiC. Materials annealed with pressure exhibited a fine microstructure with equiaxed grains when the phase transformation from beta -Sic to alpha -SiC was < 30 vol%, whereas materials annealed without pressure developed microstructures with elongated grains when phase transformation was > 30 vol%. These results suggested that the precise control of phase transformation in SiC ceramics and their mechanical properties could be achieved through annealing with or without pressure.