Metal matrix composites are currently being considered for use in many applications for their high strength-to-weight and stiffness-to-weight ratios, high wear resistance, and high thermal resistance. The present work focuses on the study of crack propagation in Aluminum monolithic and aluminum metal matrix composites reinforced with continuous stainless steel fibers at 4%, 8%, and 13% volume fractions with five plies, and unidirectional structural configuration. Based on experimental evidence, a micromechanical modeling approach was developed for the prediction of fatigue life and the model was compared with actual fatigue lives for these materials.