Selective Laser Sintering (SLS) is a 3D printing process on a powder bed that presents a real revolution for many industrial sectors, it allows to produce layer by layer precise prototypes, fast, with high dimensional accuracy and with remarkable mechanical characteristics. This technology uses a laser to fuse polymer micro particles, following the geometry of digitally cut CAD models. However, the external surfaces of the parts produced by this process are characterized by a high degree of roughness due mainly to the properties of the powder, the orientation in the build-up tray and the manufacturing parameters. In this study selective laser sintering experiments were performed with PA12 powders, in order to analyze the optimal process parameters for the realization of parts with minimal roughness. The process parameters chosen for the study were carefully selected and which are laser power, scanning speed, layer thickness and scanning space. The samples were printed in different orientations 0°, 45° and 90°. The Taguchi method was used to study the parameters. Regression equations for each of the orientations were established, these developed a linear relationship between the roughness and the parameters studied.