Background: Patients who are often in life-threatening conditions are placed in intensive care units. Working in such a department, where the patient's condition is constantly changing and where the percentage of deaths is higher than in other departments, brings with it specific difficulties. Acting in situations contrary to one's moral values, witnessing suffering, and feeling powerless as nurses can lead to symptoms of the stress of conscience and moral injury. Aim: Investigate and determine the level of stress of conscience, the ethical conditions of the work environment and the correlation with moral injury among nurses working in intensive care units. Methods: The research was conducted in intensive care units in 6 hospitals. Data were collected in the period from February to August 2023. Each subject signed an informed consent, and the instrument consisting of three questionnaires, the Hospital Ethical Environment Questionnaire (HECS), the Stress of Conscience Questionnaire (SCQ), and the Moral Injury Symptom Scale-Health Professional Version (MISS-HP) was used to collect data. Data are analysed using descriptive statistics. Furthermore, an exploratory factor analysis was performed for all three questionnaires, and a confirmatory factor analysis was performed for the Stress of Conscience Questionnaire. Results: In the research study, 186 nurses participated. The study demonstrated the correlation between the ethical work environment and the development of stress of conscience and moral injury symptoms (r=0,421; p<0,01). The findings have shown that an ethically pleasant work environment reduces the stress of conscience and moral injury. Education and work experience do not play a role in the development of stress of conscience and moral injury. Out of 186 respondents, 119 (63.9%) demonstrated the presence of moral injury symptoms. Conclusion: Stress of conscience and moral injury are relatively unknown concepts in Croatia, although medical professionals often encounter their symptoms. Working in emotionally and psychologically demanding departments leaves short-term and long-term traces on an individual. That is why it is essential to raise awareness about them, educate medical workers about them, and promote an ethically pleasant working atmosphere as one of the most critical prevention mechanisms. It is necessary to encourage the verbalisation of dilemmas, asking questions and improving communication within the team. Finding a good balance between work and private life is essential, as well as discovering ways to release stress, allow yourself feelings, and know how to deal with them.