Background Ethical decision making in intensive care is a demanding task. The need to proceed to ethical decision is considered to be a stress factor that may lead to burnout. The aim of this study is to explore the ethical problems that may increase burnout levels among physicians and nurses working in Portuguese intensive care units . A quantitative, multicentre, correlational study was conducted among 300 professionals.Results The most crucial ethical decisions made by professionals working in ICU were related to (...) communication, withholding or withdrawing treatments and terminal sedation. A positive relation was found between ethical decision making and burnout in nurses, namely, between burnout and the need to withdraw treatments , to withhold treatments and to proceed to terminal sedation . This did not apply to physicians. Emotional exhaustion was the burnout subdimension most affected by the ethical decision. The nurses' lack of involvement in ethical decision making was identified as a risk factor. Nevertheless, in comparison with nurses , it was the physicians who more keenly felt the need to proceed to ethical decisions in ICU.Conclusions Ethical problems were reported at different levels by physicians and nurses. The type of ethical decisions made by nurses working in Portuguese ICUs had an impact on burnout levels. This did not apply to physicians. This study highlights the need for education in the field of ethics in ICUs and the need to foster inter-disciplinary discussion so as to encourage ethical team deliberation in order to prevent burnout. (shrink)