Many hospital radiology departments are adopting "lean" methods developed in automobile manufacturing to improve operational efficiency, eliminate waste, and optimize the value of their services. The lean approach, which emphasizes process analysis, has particular relevance to radiology departments, which depend on a smooth flow of patients and uninterrupted equipment function for efficient operation. However, the application of lean methods to isolated problems is not likely to improve overall efficiency or to produce a sustained improvement. Instead, the authors recommend a gradual but continuous and comprehensive "lean transformation" of work philosophy and workplace culture. Fundamental principles that must consistently be put into action to achieve such a transformation include equal involvement of and equal respect for all staff members, elimination of waste, standardization of work processes, improvement of flow in all processes, use of visual cues to communicate and inform, and use of specific tools to perform targeted data collection and analysis and to implement and guide change. Many categories of lean tools are available to facilitate these tasks: value stream mapping for visualizing the current state of a process and identifying activities that add no value; root cause analysis for determining the fundamental cause of a problem; team charters for planning, guiding, and communicating about change in a specific process; management dashboards for monitoring real-time developments; and a balanced scorecard for strategic oversight and planning in the areas of finance, customer service, internal operations, and staff development.