Companies should focus on adopting the most suitable initiatives that support in satisfying their customer needs. Lean is considered as one of the most important initiatives that enhance the internal processes; hence, significant results can be achieved. On the other side, it is crucial to sustain such results over time. In order to achieve such sustainability, companies need to identify and strengthen the lean success factors before establishing a lean program. In this paper, Fuzzy-DEMATEL method is used to identify such factors. The proposed approach is applied in an Egyptian factory. Before the identification of lean critical success factors, the company tried to implement lean applications. Positive results were achieved but on the long run, the system restored its initial performance levels. After applying the proposed approach, it is concluded that “Education and training”, “Top management involvement”, “Leadership” and “Cultural change” are the critical factors and should be strengthen before lean consultant participations. After working on such factors, continual improvement is achieved and remained since 2015. On average there are 60 KAIZENs (improvement actions) are executed monthly in that firm. Moreover, reducing of work-in-process and improving production rate are continually improved even after closing the lean training program.