59Background Moral distress in registered nurses causes decreased job satisfaction, turnover in staffing, burnout, and heightened states of psychological distress. To date, investigation of modifiable factors, such as perceptions of the practice environment and patient safety, among a diverse sample of critical care nurses has been limited. Objective To explore the relationships among the severity of moral distress, the practice environment, and patient safety in a national sample of critical care nurses. Methods Critical care nurses experienced in working with adults (> 1 year of intensive care unit experience) and who were subscribers to the American Association of Critical-Care Nurses' e-mail listserv and social media sites anonymously participated in this descriptive study. Participants completed a demographic questionnaire, the Moral Distress Scale-Revised, and the Practice Environment Scale of the Nursing Work Index. Descriptive statistics, bivariate correlation coefficients, and a hierarchical regression analysis were used to describe the sample characteristics and to assess relationships among the study variables.Results Of a national sample of 328 critical care nurses, 56% had less than 20 years of experience as a registered nurse. Moral distress was modestly associated with negative perceptions of the practice environment and patient safety. Job satisfaction, practice environment, and the participant's age were statistically significant predictors of moral distress in this sample. Conclusions Modifications of organizational factors such as the development of healthy work environments that promote collegial relationships could reduce moral distress among critical care nurses.