Summary Objective: Lack of access to updated drug information is a challenge for healthcare providers in Norway. Drug charts are updated in separate EHR systems but exchange of drug information between them is lacking. In order to provide ready access to updated medication information, a project for consent-based access to a core EHR has been established. Methods: End users have developed requirements for additions to the medication modules in the EHR systems in cooperation with vendors, researchers and standardization workers. The modules are then implemented by the vendors, tested in the usability lab, and finally tested by the national testing and approval service before implementation. An ethnographic study, with focus on future users and their interaction with other actors regarding medicines and medication, has included semi-/unstructured interviews with the involved organizational units. Results: The core EHR uses the EHR kept by the patient’s regular GP as the main source of information. A server-based solution has been chosen in order to keep the core EHR accessible outside the GP’s regular work hours. The core EHR is being tested, and the EHR-vendors are implementing additions to their systems in order to facilitate communication with the core EHR. All major EHR-system vendors in Norway participate in the project. Conclusions: The core EHR provides a generic basis that may be used as a pilot for a national patient summary. Examples of a wider use of the core EHR can be: shared individual plans to support continuity of care, summary of the patient’s contacts with health providers in different organizations, and core EHR information such as important diagnoses, allergies and contact information. Extensive electronic cooperation and communication requires that all partners adjust their documentation practices to fit with other actors’ needs. The implementation effects on future work practices will be followed by researchers.