The comparison of the patient's current medication list with the medication being ordered when admitted to Hospital, identifying omissions, duplications, dosing errors, and potential interactions, constitutes the core process of medicines reconciliation. Access to the medication the patient is taking at home could be unfeasible as this information is frequently stored in various locations and in diverse proprietary formats. The lack of interoperability between those information systems, namely the Primary Care and the Specialized Electronic Health Records (EHRs), facilitates medication errors and endangers patient safety. Thus, the development of a Patient Summary that includes clinical data from different electronic systems will allow doctors access to relevant information enabling a safer and more efficient assistance. Such a collection of data from heterogeneous and distributed systems has been achieved in this Project through the construction of a federated view based on the ISO/CEN EN13606 Standard for architecture and communication of EHRs.