Aim. This paper reports a study to describe and interpret the meaning of being on long-term mechanical ventilation. Background. Patients who require mechanical ventilation in a critical care unit for prolonged periods of time are typically sicker than those who are ventilated for shorter periods. Despite advances in treatment modalities for critically ill patients, many still require long-term mechanical ventilation for 7 days or more. Therefore, caring for a long-term ventilated patient is often an everyday occurrence for critical care nurses; however, there is insufficient evidence of the meaning of this experience from a patient perspective. Method. We used an ontological phenomenological approach informed by the ideas of Heidegger. Data were collected using unstructured audio-taped interviews with nine former patients from critical care units unit in Queensland, Australia. The data were collected between January 2000 and December 2001 and alysed thematically using the method developed by van Manen. Findings. Thematic alysis revealed four themes. This paper presents the findings from the theme titled 'existing in an uneveryday world', which revealed what it meant for participants to exist, live through and survive the many physiological and psychological effects arising from their critical illness episode. For the most part, this was an unpleasant and frightening experience that involved bizarre nightmares and ibility to distinguish time, place and the familiar body; disagreeable effects from the technology used and patient care activities; and reliance on exterl agents for survival. In addition, participants reported how they questioned their chances of surviving the critical illness ordeal. Conclusion. There is a need for further research in the areas of sedative and algesic magement in critically ill patients, methods of communicating with intubated and mechanically ventilated patients, and debriefing and follow-up support services for survivors.