A Good evaluation practice in Health Informatics (GEP-HI) Evaluation Practice guideline has been developed through a consensus making process. The guideline lists a set of 60 issues that are relevant for planning, implementation and execution of an evaluation study in the health informatics domain. These issues cover the phases of an evaluation study: Study exploration, first study design, operationalization of methods, detailed study design, execution and finalization of an evaluation study. In this seminar we walk through a case study to present how to plan a health information system evaluation study applying the good evaluation practice guideline.