Although requirements analysis is acknowledged as a critical success factor of information system development for organizations, problems related to the requirements stage are frequent. Some of these problems are lack of understanding of the business by system analysts, lack of focus on the purpose of the system, and miscommunication between business people and system analysts. As a result, an information system may not fulfil organizational needs. To try to prevent these problems, this paper describes an approach based on business process modelling and purpose analysis through BPMN and the goal/strategy Map approach. The business environment is modelled in the form of business process diagrams. The diagrams are validated by end-users, and the purpose of the system is then analyzed in order to agree on the effect that the information system should have on the business processes. Finally, requirements are specified by means of the description of the business process tasks to be supporte...