Production Data Systems are those systems that involve the Systems and Applications designed to provide information about production status, present or historical, in several ways: providing instrument data about temperature, flow, pressure, and online analyzers; offering laboratory data about quality of products; and managing the stocks of storage elements, internal transfers, etc. The PI System is involved in these systems and acts in two ways: as a data shuttle to the rest of the production systems and offering a real-time vision of the Plant. So, the PI System is the interface between the plant and the IT world as well as a Production Data System itself. This presentation will show the role of the PI System in Repsol YPF Refineries Production Data Systems layout, along with the Laboratory Information Management System (LIMS) and the Production Management System.