The mechanical properties of Al 2 O 3 matrix composites reinforced by ZrO 2 (2 mol% Y 2 O 3 ) and nanometre scale SiC dispersions have been investigated. It is shown that the Al 2 O 3 matrix is simultaneously strengthened and toughened by both ZrO 2 (2 mol% Y 2 O 3 ) and nano-SiC particles. The maximum flexural strength and fracture toughness of the composites are 945 MPa and 7.3 MPam 1 2 , respectively. The reinforcing effect of both t-m phase transformation of ZrO 2 (2 mol% Y 2 O 3 ) and nano-SiC particles appears to be synergetic.