Metal matrix composites (MMC) that consisted of Al (-Mg) matrix reinforced with initially added BN particles were fabricated using the pressureless infiltration technique. Initially added BN particles were partly consumed to make AlN, as new reinforcing particles. The other reaction product was MgAlB2 dispersoids. The creep behavior was investigated between 225- 275oC in air. Despite of the presence of the reinforcing particles, the creep resistance was found to be unsatisfactory due to the weak Al (-Mg) matrix.