B4C based ceramics composites with 0-25 mol% CrB2 were fabricated by pressureless sintering in the temperature range 1850degreesC to 2030degreesC. The CrB2 addition enhanced the densification of B4C due to the CrB2-B4C eutectic liquid phase formation. Both a high strength of 525 MPa and a modest fracture toughness of 3.7 MPa m(1/2) were obtained for the B4C-20 mol% CrB2 composite with a high-relative density of 98.1% after sintering at 2030degreesC. The improvement in fracture toughness is thought to result from the formation of microcracks and the deflection of propagating cracks resulting from the thermal expansion mismatch of CrB2 and B4C.