A possibility of production of aluminium matrix composites by using the lost foam process was investigated. Silicon carbide particles, graphite particles, and stainless steel wires were used as reinforcement materials. The reinforcement materials were introduced to the polystyrene to form patterns via injection molding process. The results obtained from this experiment can be summarized as follows. In Al/SiC_p system, the particles with the radius of 100㎛ and over were entrapped in the matrix in the case of upward freezing of which solidification direction was opposite to floating direction of the particles. And few particles were entrapped in the matrix in downward freezing. In Al/graphite system, almost no particles were entrapped in the matrix except the area chill attached. When the thickness of polystyrene slice was 4㎜ in Al/stainless steel wire system, the floating tendency of fibers was observed to increase as the distance from the ingate was increased.