This thesis is focused on the logical design of the information system for records and analysis of blood donation in the Republic of Croatia. The intention of the proposed system is to improve the efficiency and accuracy of data collection, monitoring and analysis, which ultimately achieves more effective blood supply management. The goal of the research is to contribute to the development of a more efficient system of blood donation and blood transfusion in Croatia through the results of the research, which will ultimately improve the health outcomes of patients who need blood products during transfusion. Various methods are used to achieve this goal, including stakeholder interviews. It provides a clear picture of the operation of the current Croatian blood donation system and its limitations. The initial part of this work is focused on establishing the theoretical basis that serves to create the model. Provides a detailed explanation of fundamental concepts such as information systems, data and process modelling, data flow diagramming, and normalization. In addition, the description of the system itself is explained in more detail, as well as the stated legal regulations and determinants that affect its operation. The second part of the paper presents the design of the blood donation information system, which is designed on the basis of the existing information system. The visualization of the system itself is shown using a data flow diagram and a conceptual (ER) data model that translates into a relational (RM) data model. The rules of normalization, which test the correctness of creating normal forms, are also explained and, finally, the algorithms for obtaining essential information from the relational data model are also presented.