This paper provides an overview of environmental sustainability in healthcare and highlights the need for a policy framework for action. Examples from overseas demonstrate what has effectively enabled mitigation of and adaptation to the threat of climate change. The need to overcome perceived limits and barriers to health professionals' engagement in sustainable practice is noted. The scientific evidence recommends immediate action. What is known about the topic? Climate change has negative impacts on human health. There are co-benefits in mitigating and adapting to climate change that will benefit both humans and health systems, increasing wellbeing, financial and health system efficiency. There is a need for health professionals to engage with sustainability. Australia's health policy makers could learn useful lessons about how to be sustainable from the significant policy and legislation work occurring elsewhere. What does this paper add? This paper reports on the context of and need for becoming sustainable in healthcare. It provides brief examples of what has occurred in other countries and advocates for a policy framework to support further action in Australia. What are the implications for practitioners? The significance of this paper is that it notes the need for a consistent, whole-of-country approach to carbon reduction in many aspects of the healthcare system. From an increased preventative focus on population health, coupled with actions in patient care, and developing a whole-of-healthcare-system approach, benefits will be realised that serve to reduce carbon emission, thereby tackling the longer-term effects of climate change. This view is supported by the noted success of increasing sustainable health system actions in the United Kingdom National Health Service and elsewhere.