In this study, Al-MgO reinforced metal matrix composites of 5%, 10%, and 15% reinforcement-volume ratios were produced by melt-stirring, and some mechanical properties and microstructures of composite specimens were examined. Subsequently, the produced metal matrix composites materials were machined in computer numerical control lathe by two different cutting tools, namely, carbide and coated carbide cutting tools. Machining tests were performed at the cutting speeds of 150, 200, 250, and 300m/min, at the feed rates of 0.075, 0.15, and 0.225mm/rev and at a constant depth of cut (1mm). The surface roughness of machined composites was measured, and the average surface roughness (Ra) values were identified. While surface roughness value was found to decrease with increased cutting speed, it increased with the increase in feed rate. In all machining processes, the highest surface roughness values were obtained at 150m/min cutting speed. The poorest machinability in terms of surface roughness was obtained in 15% MgO reinforced specimen. In general, the highest surface roughness quality was obtained with carbide cutting tools in all reinforcement-volume ratios, whereas coated carbide cutting tools performed better in 15% MgO reinforced specimens and at 300m/min cutting speeds.