The paper deals with the use of Lean Manufacturing tools in improving the production process of car arm rests in a car manufacturing company in Poland. The article describes the original condition of a single production process of assembling ready pieces to produce car arm rests. The original condition was assessed and described with the use of some basic Lean indicators and value stream mapping. The aforementioned tools allowed to assess the process condition and to identify the organizational issues and their sources. It also enabled to reorganize the process and increase its efficiency. The further part of the article describes the results of improvement actions. The process assessment was held and improvements introduced in the first quarter of 2018.