One of the many advantages of low pressure carburizing (LPC) is that it can be combined with high-pressure gas quenching. This makes it possible to achieve workpieces with pure metallic surfaces, less distortion hardening, and, above all, it allows a more reliable and repeatable treatment than conventional oil quenching. This article presents a study of the distortion rate of workpieces carburized at low pressure then quenched in nitrogen at 1.4MPa. By comparing the distortion which takes place during the carburizing stage only and the carburizing combined with post-carburizing heat treatment it will be possible to assess the distortion rate and its causes at the different stages of the heat treatment process.