The addition of Y3Al5O12 (YAG) into the ZrB2-SiC composites was investigated in the present research. Composites were densified by SPS method at 1850ºC under a uniaxial pressure of 50 MPa for 20 min. Microstructural evaluation and mechanical properties were evaluated with a various content of YAG (1-5 wt%). The microstructural and phase analysis showed that incorporation of YAG promoted the densification process from the solid-state sintering to liquid phase sintering. The highest density (99.81% RD) and fracture toughness (6,44 ± 0.23 MPa.m1/2) were obtained for the composite containing 5 wt % YAG after the SPS process. Although hardness and elastic modulus of samples were decreased with the increasing of YAG amount, measured values were comparable with the literature.