Background: Moral distress and ethical climate are important issues in the workplace that appear to affect people's quality of work life. Objectives: This study was conducted to determine the relationship of moral distress and ethical climate to job satisfaction in critical care nurses. Materials and methods: This descriptive-correlation study was conducted on 142 critical care nurses, selected from five social security hospitals in north Iran through census sampling. Data were collected using a demographic questionnaire, the Moral Distress Scale-Revised, the Olson's Hospital Ethical Climate Survey, and the Brayfield and Rothe Job Satisfaction index. Ethical considerations: The research project was approved by the Ethics Committee of Mazandaran University of Medical Sciences and the Medical Deputy of the Social Security Organization. Findings: The mean scores obtained by the critical care nurses for moral distress, ethical climate, and job satisfaction were 87.02 +/- 44.56, 3.51 +/- 0.53, and 62.64 +/- 9.39, respectively. Although no significant relationships were observed between moral distress and job satisfaction, the relationship between ethical climate and job satisfaction was statistically significant (p < 0.05). Conclusion: Identifying ethical stressors in the workplace and giving proper feedback to the authorities to eliminate these factors and improve the ethical climate in these workplaces can help enhance job satisfaction in nurses and lead to higher quality care.