Using micrometer- and nano-sized SiC particles as reinforcement phase, two ZrB2-SiC composites with high strength up to 1600 degrees C were prepared using high-energy ball milling, followed by hot pressing. The composite microstructure comprised finer equiaxed ZrB2 and SiC grains and intergranular amorphous phase. The temperature dependency of flexure strength related to the initial particle size of SiC. In the case of micrometer-sized SiC, the high-temperature strength was improved up to 1500 degrees C compared to room-temperature strength, but the strength degraded at 1600 degrees C, with strength values of 600-770 MPa. In the case of nano-sized SiC, the enhanced high-temperature strength was observed up to 1600 degrees C, with strength values of 680-840 MPa.