Nowadays, the highly competitive market makes industrial companies search for new decisions to improve their competitive advantages. It can be lowering product cost, manufacturing and delivering faster than competitors or being flexible when producing different quantities of different products for different customers. Most popular instruments that help companies to reach previously mentioned competitive advantages are implementing Lean Manufacturing strategies or ERP systems into their production systems. The way of using these systems might become the main indicator of companies’ success in the future. This research aims to create a guideline for integrating ERP system into Lean Manufacturing system. It focuses on the manufacturing companies that are already using such a system and can share their good and bad experiences. To reach this aim, the scientific literature is being analyzed by retrieving the CSFs for such an integration process. Using these CSFs, the relation between them and the positive outcomes of the integration process is established and tested using an online survey. The results of the survey are processed using empirical methods. Moreover, the research methodology for evaluating the ERP system integration into Lean Manufacturing level is established and tested in three case analyses.