This paper presents a case study on the development and implementation of an executive financial information system. The initial part of this research was to discuss the research objectives with executives of the case firm to clarify system functions for executive financial decision support, including financial analysis, internal audit, and relationship management. By doing so, this research begins to design and implement prototype executive information systems using in-depth interviews, system planning, relational database design, prototype system implementation, as a multi-stage research methodology. Some managerial issues and discussion are presented. In addition, limitations and future works are described. Thus, this is not only the practical development of an executive financial information system development, but also an academic research to explore the system implementation process in terms of organization, members, business functions, system procedure and information systems.