A mixture of Zr, B4C, and Si powders was adopted to synthesize a ZrB2-SiC composite using the spark plasma sintering-reactive synthesis (SPS-RS) method. SPS treatments were carried out in the temperature range of 1350 degrees-1500 degrees C under a varying pressure of 20-65 MPa with a 3-min holding time. A dense (similar to 98.5%) ZrB2-SiC composite was successfully fabricated at 1450 degrees C for 3 min under 30 MPa. The microstructure of the composite was investigated. The in situ formed ZrB2 and SiC phases dispersed homogeneously on the whole. The grain size of ZrB2 and SiC was < 5 and 1 mu m, respectively. A number of in situ formed ultrafine SiC particles were observed entrapped in the ZrB2 grains.