Hospitals serve an important need and use scarce and valuable resources. Yet many hospitals perform poorly, under-utilising key facilities such as operating rooms, offering poor access to patients with urgent needs and keeping patients in hospital longer than required or discharging them before they are fit. A vital element of managing a hospital is patient flow: who is admitted, how interventions are scheduled, how the patient progresses form one stage of treatment to the next and how discharge is managed. In summary, how resource and loading are balanced across the system. Yet in many hospitals this process is not managed actively as the staff lack the both the awareness and necessary skills. Lean thinking can help but simple solutions do not work in complex environments. Peter Willats will talk about his experience of redesigning patient flow in a leading London hospital using a combination of advanced lean techniques and data analytics.