The Information Technology Infrastructure Library (ITIL) is a collection of best practices for the management of IT services. ITIL helps organizations to become aware of the business value their IT services provide to internal and external stakeholders. Understanding this value is crucial to the definition of Service Level Agreements (SLA) between an IT department and its stakeholders. However, it is not ITIL’s objective to define how this value is to be elicited from stakeholders. This creates an opportunity for the use of RE methods in businesses. This paper describes the main principles of ITIL Service Management and illustrates how the SEAM RE method can contribute to the definition of an SLA by modeling the service provided by an IT departments, the stakeholders of this service and the value the stakeholders expect from this service. A real industrial example is presented and analyzed.