Integration is a challenging problem that has tormented businesses for many years. Enterprise Resource Planning (ERP) systems are enterprise-wide systems that automate all of a company's business processes and replace legacy systems, integrating all departments and functions across a company in a single computer system that runs off a single database so that the various departments can more easily share information and communicate with each other. In this paper, the preparation analysis and the necessary steps for the implementation of an ERP system in a construction industry in Greece are described. Finally, the challenges concerning the implementation are presented.