The aim of this study was to evaluate the influence of the amount and distribution of inclusions of titanium carbonitride and manganese sulfide on the machinability and polishability of Villares VP100 steel which is used in manufacturing polymer injection molds. By means of materials metallography, captured images were processed with image analysis software to characterize the inclusions. Tool life tests were performed in an open cavity in order to approach the real processes situation found in the toolmaking industry. The flank wear and chip formation were evaluated periodically. The cutting forces were also evaluated under the same conditions applied to the tool life test. The polishing tests were performed in a polishing equipment specially developed for this purpose, which allows adjustable rotation speed and pressure load. In the polishing process, abrasives with particle size of 1mm are applied and surface roughnesses of the samples were evaluated according to the polishing time. The results show that the amount of titanium and size of titanium carbonitride hard inclusions are fundamental for good machinability, while the soft sulfides of manganese do not take any effect in the presence of these hard particles. The polishability is worsened by the presence of large inclusions of manganese sulfides, forming pin holes.