Introduction: As Information Technology (IT) becomes more and more advanced, the Enterprise System (ES) starts to attract researcher’s attention. While with the high rate of failure IT projects, it is important to evaluate the IT project properly. This paper conducts a case study in the Health Care area and chooses Jönköping County Council’s ROS system to be the target system. According to the established linkage between theory and real world organization, a practice of Enterprise System Evaluation is conducted by using an existing Uwizeyemungu et al.’s Enterprise System Effects Evaluation Model (ESEM). The research questions are as follows: What are the Enterprise Systems Effects which impact on business processes? To what extend do the ES effects impact on the business processes? Purpose: the study is an exploratory study that aims at identifying what are the ES Effects which impact on the business processes and assessing the importance and the actual degree of these effects. The answers of the first goal are explored by analyzing the documents and the record of interview, and the results are the basis of the second question. Method: This research has adopted a combined approach because of the nature of the research questions. Data has been collected through face-to-face interview, survey and the organizational documents. Secondary data are also be used for analyzing. Both qualitative and quantitative data are used for getting a reliable conclusion. Conclusions: The Enterprise System effects can be categorized into automaional effects, informational effects and transformational effects. The relationship between such effects and Performance indicators are very important. By determining the importance and impacts degree of such relationships, the evaluation results can be explicitly calculated and understood.