The aim of the National Health Service (NHS) is to provide access to medical care to all. One of the challenges is to balance demand and resources while avoiding unduly long waiting lists, either for treatment (the 'traditional' waiting list phenomenon), or to see a practitioner. This note illustrates how Systems Thinking can contribute to the understanding of this complex issue, and to assessing the impact of various policies. Systems thinking differs from traditional approaches in that it looks at the problem as a whole, as a system, and focuses on identifying key inter-relationships and feedback loops between different components of the system. We present three simple examples which illustrate the concepts of systems thinking, and indicate how this approach could be useful to analyse various policies.