Global climate change is no longer an ominous future threat but a dawning reality – one that is already creating disturbing shifts in the natural and human environment and eroding the delicate balance of our planet’s ecosystem and the species that depend on it. This discussion draft is based on the World Health Organization’s (WHO) mandate from member states to develop “programmes for health systems that will contribute to reducing their own greenhouse gas emissions”. It also takes root in Health Care Without Harm’s (HCWH) more than 12 years of experience of working globally to transform the health sector so that it is no longer a source of harm to human health and the environment. The paper begins to define a framework for analysing and addressing the health sector’s climate footprint – including identifying seven aspects of a climate-friendly hospital. It also draws on a series of examples from around the world that demonstrate that the health sector is indeed already beginning to provide leadership in this most important area of concern to the global community. This paper is the first step in a WHO project in collaboration with Health Care Without Harm (HCWH) aimed at addressing the climate footprint of the health sector.