We investigated the influence of cutting parameters on surface roughness when machining Inconel 718 using a carbide (K5000-U) end mill. A series of experiments were carried out to find a suitable range of machining parameters. A design technique was used to reduce the number of experiments through differing combinations. Response surface methodology was used to develop a predictive model and an analysis of variance was employed to validate it. The model was also validated with additional experiments and showed good agreement. The results show that a combination of high cutting speed with a low feed rate and depth of cut achieved a good surface finish. It was observed that the depth of cut had a greater influence on surface quality than the feed rate or cutting speed.