Abstract Background There is growing recognition of the significance of a close collaboration between patients, clinicians, and researchers to ensure that research and health service delivery effectively meets the needs of end users [1-3]. However, there is limited understanding of best practices for patient engagement in research among patients with venous thromboembolism, and there is sparse knowledge about challenges to and facilitators of this process [4, 5]. Purpose To describe and explore the process and evaluate the impact of patient engagement in the development of a structured nurse-led post pulmonary embolism care model (the Attend-PE model). Method This prospective embedded case study of patient engagement was conducted within the research project - A structured Integrated post Pulmonary Embolism care model (Attend-PE). The study was based on documents from patient journey mapping (PJM), documents and field notes from workshops, and semi-structured interviews with two patients with pulmonary embolism, two clinicians working with pulmonary embolism patients and the Attend-PE researchers. Data were analyzed based on research questions guided by the United Kingdom six Standards for Public Involvement; Inclusive opportunities, Working together, Support & learning, Governance, Communications and Impact [6]. Result Patients played a crucial role throughout the entire Attend-PE study, contributing to research questions, design, execution, and dissemination, as illustrated in Figure 1. The patients were involved at a higher engagement level in the co-creation of the Attend-PE model and co-creation of patient education and information material. Comparatively the engagement level was lower in decisions regarding outcomes, feasibility testing and implementation of the Attend-PE model, as shown in Figure 2. Notably, despite lower engagement level, the continuous involvement in the research process was invaluable to the patients. This ensured that they maintained insight in the research process, even though their contributions varied in the different phases. Important facilitators of patient engagement within the Attend-PE were related to "Inclusive opportunities" and "Support and learning". Patients highlighted the importance of being a part of the process, working together as a team, and being prepared for the work. Important challenges to patient involvement related to "Communication" and "Governance", including lack of expectation alignment and communication regarding clinical elements where clinicians often dominated the discussions. Conclusion Patient involvement has been invaluable in the development of a structured nurse-led post pulmonary embolism care model. Further, patients will be involved in evaluation of the national implementation process and dissemination of study results.Figure 1Figure 2