SummaryAim of paper This paper will report a research study conducted to compare the perceptions of nurses and relatives of critically ill patients on the importance of the caring behaviours of critical care nurses.Background The concept of caring is central to the nature of nursing with many approaches to defining and describing it in the nursing literature. Caring in critical care nursing involves affective, cognitive and action processes. It is the action processes or caring behaviours that are most evident to nurses, patients and relatives.Method This descriptive, comparative, quantitative study was conducted in an Irish critical care setting. Convenience sampling was used to recruit n = 40 nurses and n = 30 relatives of critically ill patients. Data were collected over a 3-week period in 2006 using an adapted version of the Caring Behaviours Assessment Tool. Descriptive statistics were used to analyse the data.Findings There was congruence between nurses and relatives on the most and least important caring behaviours of critical care nurses. Both groups placed a higher value on caring behaviours which demonstrate technical competence, the altruistic and emotional aspects of caring.Conclusion The results of this study have demonstrated that there are more similarities than differences between the perceptions of nurses and relatives on the importance of the caring behaviours of critical care nurses. The results of this study will give critical care nurses a greater understanding of how their caring behaviours are perceived by others. Incorporating the views of relatives into the delivery of care in the context of critical care will allow nurses to create a patient-centered service.