Background <p>Healthcare delivery produces substantial emissions that contribute to climate change and harm human health. Patient perspectives on ethical dilemmas, such as tradeoffs between individual health choices and public health harms mediated by climate change, are unclear.</p> Methods <p>This cross-sectional survey randomly sampled adult patients across four US health systems to assess their perspectives on ethical dilemmas in climate change and healthcare delivery; results were compared to a previous nationwide survey of US-based physicians. The mailed survey was developed iteratively through pre-testing and was designed to detect a 15% difference in the proportion willing to limit treatment options because of environmental impact according to respondents’ perceived impact of climate change on their health. Secondary outcomes included physician responsibilities for healthcare sustainability and acceptability of environmentally motivated treatment tradeoffs.</p> Results <p>Between 11/2023 and 9/2024, 289 of 516 patient surveys and 304 of 529 physician surveys were delivered and returned, for response rates of 56.0% and 57.5%, respectively. Most patients (79.1%) believed that environmental factors impacted their medical conditions, and 36.3% reported a moderate-to-high health impact from climate change, while 5.2% reported speaking with their doctor about climate and health interactions a moderate amount or more. Similar proportions of patients (35.8%) and physicians (35.0%) agreed with reducing healthcare’s environmental impact even if it required limiting treatment options. Like physicians, patients’ perceived health impact (moderate-to-high versus low-to-no) was associated with willingness to place such limits (adjusted OR 1.85; 95% CI 1.01, 3.41). Most patients (77.1%) were willing to accept some reduction in the likelihood of treatment response if that treatment was less environmentally impactful; unlike physicians, this did not vary by health impact (adjusted OR 1.16; 95% CI 0.63, 2.20). Almost all patients (96.8%) reported that physicians should help make healthcare sustainable, and 64.7% thought this included changing clinical practices.</p> Conclusions <p>Many US patients and physicians recognize connections between health, healthcare delivery, and climate change, and accept environmentally motivated treatment tradeoffs, but do not discuss them in the clinic. Patient views largely parallel those of physicians, suggesting support for climate-informed medical practice and for incorporating environmental considerations into clinical decision-making.</p>