The purpose of this work is study the behavior of the internal flow in screw compressors. These machines are widely use in refrigeration, air conditioning, automotive field and industrial applications since they are very reliable and can reach good efficiency. Screw compressor performances are affected mostly by the tooth profile. In particular, parameters as sealing line and blow hole area must be minimized. Unfortunately profile curves and geometrical parameters, such as undercutting limits, are usually not available in the literature due to the need of manufacturing companies to protect their know-how and so it is difficult to find validation test cases.