ABSTRACT Patient flow in emergency departments (EDs) is notoriously difficult to manage efficiently. While much of the attention has focused on the procedures, protocols and pathways in which patients receive their first hours of care, less attention has been paid to the relational factors that make it happen. Our study is the first, to our knowledge, to consider the role of interprofessional barriers, defined as suboptimal ways of working, as perceived by ED staff in patient flow management. Drawing on 19 interviews with hospital staff in an acute tertiary trauma center hospital in England, we established three flow-related types of interprofessional barriers: ED teamwork barriers, performance-driven coordination barriers, and referral-related collaborative barriers. Knotworking was recognized as a form of interactions and asset to teamworking, coordination, and collaboration. Identifying processes such as chasing, escalating, and advocating enabled our investigation to highlight a very complex set of interprofessional interactions, and signpost what the suboptimal practices of flow management are. Our analysis holds promise for hospitals beyond the National Health Service in England.