AIM: This paper is a report of a study to interpret nurses' experiences of moral strength in practice. BACKGROUND: Moral strength is said to be beneficial in providing nursing care for patients, thereby contributing to high qualitative care. However, few studies focus on the meaning of nurses' moral strength. METHODS: This study included eight Registered Nurses working in different aspects of health care in southern Sweden. Individual interviews were conducted in 2006 and 2007. We recorded, transcribed verbatim, and interpreted the interviews by a method grounded in hermeneutics. FINDINGS: Three themes were interpreted on three different levels: the action level as 'having courage to act on one's convictions', the relational level as 'being attentive and recognizing vulnerability', and the existential level as 'facing the unpredictable'. Overall, moral strength was understood as a driving force to be someone special in the care of patients, i.e. someone who makes a difference. CONCLUSION: The value of nurses' moral strength in patient care should be recognized. Attention must be given to aspects outside the individual, e.g. professional and institutional processes that influence the work environment. Clinical team supervision can help make such processes visible and supportive.