Roller burnishing process was applied to Al2O3/A356 composite specimens,. The process was carried out on vertical milling machine. Effects of the burnishing process with varying process parameters on the characteristics of the machined surface and sub-surfaces were investigated. Residual stress distribution at different depths beneath the burnished surfaces, microhardness distribution, surface roughness were used as criteria to obtain the optimum burnishing conditions that give burnished surfaces with high integrity for the Al2O3/A356 composite. Results showed an improvement in surface characteristics of Al2O3/A356 composites using burnishing process. The better surface roughness was obtained with double passes burnishing, depth of penetration of 0.12 mm, and burnishing speed of 72 mm/min. Increase of number of burnishing passes increases the value of residual compressive stress and the microhardness at the burnished surface and subsurface. The microhardness slightly decreased with the increase of burnishing speed.