Nowadays business atmosphere is to constantly come up with new improvements, in order to become more competitive, or simply stay competitive.Lean manufacturing rose up few decades ago and is now famous for its radical improvements but also for its difficulty to implement. The aim of this study is to get a better understanding of how can Lean bring such important changes, but also what must be done in order to implement it.In order to solve the problem of this report, it was decided to conduct a quantitative research relying on a case study. The company chosen wants to implement Lean but does not really know how to achieve it, so it is a very good opportunity for this project to collaborate with it and see what can be done to implement Lean manufacturing.The results of this thesis demonstrate the need of implementing a philosophy, a way of thinking, rather than different production tools. People must also be prepared for long implementation, which can take between 5 to 10 years. One of the key factors for this implementation is the involvement and empowerment of workers, who will massively contribute to the change process by removing different kind of waste which slow down the processes.