In this study, machining parameters were evaluated and optimized with grey relational analysis in drilling B4C reinforced metal matrix composites (MMCs) produced by powder metallurgy. HSS, TiAlN coated and uncoated cementide carbide drills were used under dry cutting conditions. The drilling parameters such as feed rate, spindle speed, drill material and wt.% of B4C particles were optimized based on multiple performance characteristics including thrust force, torque and surface roughness. The experimental study showed that increasing the weight fraction of the B4C resulted in a considerable increase in the thrust force. Furthermore, average surface roughness of drilled hole decreased with increasing particle content for carbide tools and increased for HSS tools. Among the tools used, TiAlN coated carbide drills showed the best performance with regard to the surface roughness. Moreover, ANOVA analysis indicated that the most effective factor on grey grade was found to be weight fraction and followed by drill material, feed rate and spindle speed, respectively. (C) 2013 Elsevier Ltd. All rights reserved.