The effects of machining parameters, such as reinforcement size, machining speed and feed rate, on tensile strength, strain at break and fractured surfaces of Al-based metal matrix composites were analysed in this present investigation. It was found that larger particles (13 µm) induce higher stiffness on machined metal matrix composite parts machined at higher speed (2500 r/min) and lower feed (200 mm/min), providing constant input parameters are of low values and vice versa. The effect of reinforcement size on tensile strength is negligible and higher speed (2500 r/min) and lower feed (200 mm/min) give higher tensile strength when constant input parameters are of low values. The higher machining speed (2500 r/min) gives higher strain at break though reinforcement size and feed rate have minor effect on strain at break when the constant input parameters are of high values. When the constant input parameters are of low values, the smaller reinforcement (0.7 µm), machining speed (1500 r/min) and feed rate (200 mm/min) give higher strain at break. Ductile fracture occurs in all cases regardless of input variables and smaller nodules were formed on fractured surface in the case of smaller particle (0.7 µm)-reinforced metal matrix composites.