When becoming an intensive care patient life changes dramatically. In order to save life, different actions are performed by the caregivers and the patient's ability to exercise self-determination is non-existent. After the acute phase the patient is more awake and the possibilities for self-determination change. The purpose of this study was to describe intensive care nurses' (ICNs) views of patient's self-determination in an intensive care unit and to systematize ICNs' nursing actions for supporting patient's self-determination from an action- and confirmation-theoretic perspective. In order to answer these questions, 17 interviews with ICNs were conducted by the use of the Critical Incident Technique (CIT). The transcripts were then analysed using a hermeneutic analysis method and structured by the SAUC model for confirming nursing. The main findings were that the ICN thought that the ICU patient's self-determination was low and restricted. It was more common that the ICN acted to strengthen the patient's self-determination in nursing care, but there were no specific nursing goals for patient's self-determination. The most common actions for supporting self-determination were supplying the patient with information and engaging the patient in making a day plan. The nursing implications are that the ICN's view of human being as an acting subject is important for the ICN's awareness to recognise the patient's own personal resources to handle the critically ill situation and that the ICN's competence to manifest qualified nursing is necessary for strengthening patient's self-determination.