Production of A6063/SiC-B4C hybrid composite using vacuum assisted block mould investment casting was investigated. Firstly, SiCB4C hybrid preforms were fabricated in cylindrical shape. The preferred mean particle size of the SiC and B4C powders were 60 mu m and 55 mu m respectively. In early experiments, single powder ratio of 85% SiC and 15% B4C was selected to produce the tough preforms. Subsequently, the preforms were placed into the cylindrical shape gypsum bonded block investment moulds and A6063 alloy was infiltrated into the preforms using vacuum assisted (-10(5) Pa) casting machine. Porosity fraction of preforms was determined using Archimedes' test. The fabricated cast specimens were characterized using hardness tests, image analysis and SEM observations and EDX analysis. The result indicates that, by the vacuum assisted block mould investment casting technique, the infiltration of the preforms by molten metal was successfully realized.