The purpose of this paper is to investigate the relationship/interaction between Lean and Industry 4.0. In particular, this research examines empirically the influence of Lean approach on industry 4.0 implementation in a longitudinal study. The research aims at understanding how the implementation of Industry 4.0 technologies changes during a time horizon of 3 years in companies with different level of Lean implementation. A survey has been selected to develop the longitudinal study, since it allows discovering the progression of Lean and Industry 4.0 implementation in several different plants, giving a general overview of the situation.