Service-oriented paradigm is emerging as a promising solution to handle enterprise information systems (IS) complexity, interoperability, and evolution issues. However, the shift from a conventional IS architecture to a service-oriented one is not an easy task. Various approaches have been proposed in the literature and most of them deal with either business strategic service design or a technical level IS transformation and migration. There is a need for approaches forming the link between these two levels and designing the information level transformations. In the paper, the concepts of information service and information services system (ISS) are promoted and three different ways to design information services and ISS are proposed taking into account enterprise legacy IS evolution. The three approaches are illustrated with examples taken from industrial projects and case studies.