This study examined inter-departmental relationships as a threat to patient safety in an operating department through 18 months of ethnographic research including observations and 80 staff interviews. Observations mapped organizational networks, processes, and relationships within the operating department and identified recurrent issues like bottlenecks, crisis points, and breakdowns. Interviews explored how organizational issues affected routines and work patterns in operating theatres. The findings revealed how poor relationships between departments introduced risks to patient safety in the operating department.