Secondary use of health data has gained increasing attention, especially since the COVID-19 pandemic. While hospitals have long relied on Health Data Warehouses (HDWs), primary care is now developing its own systems for data collection and valorization, opening new perspectives for data exploitation. However, the parallel development of hospital and primary care HDWs risks fragmentation, making their interconnection a key lever to improve care coordination, analyze patient pathways, and strengthen territorial health policy.This study aimed to identify the main issues, barriers, and facilitators to linking hospital-based HDWs with those from primary care, in order to understand the conditions for effective and meaningful data integration.Nine semi-structured interviews were conducted with general practitioners and professionals from public organizations involved in the regulation, organization, and governance of health data and services. An inductive thematic analysis was used to identify tensions, expectations, and potential courses of action.Results indicate a strong interest in the secondary use of primary care data, seen as a lever for research, care quality, and alignment of policies with local needs. However, support is conditional on an ethical, secure, and transparent framework. While convergence of HDWs is widely desired, significant barriers remain, including fragmented governance, lack of interoperability, cultural tensions, asymmetries in data access, and mistrust toward certain institutions. Identified facilitators include recognition of data producers, concrete feedback on data use, and shared governance. Overall, successful interconnection relies on fostering trust and demonstrating tangible utility for stakeholders.This study highlights that primary care professionals are supportive of data reuse and HDW interconnection when clinical utility is clear, feedback to contributors is meaningful, governance is transparent and inclusive, and institutional trust is established. These conditions extend beyond technical feasibility, reflecting deeper human, professional, and organizational expectations.In conclusion, linking hospital and primary care HDWs depends primarily on shared governance, trust among actors, and collective construction of meaning around data. Understanding these socio-organizational requirements is essential to harness the full potential of health data for research, quality improvement, and territorial health system planning.