Abstract: The aim of this research is to provide an analysis of the scope of nursing practice and inter-professional role responsibility for ventilatory decision-making in Australian and New Zealand intensive care units (ICU). Self-administered questionnaires were sent to nurse managers of eligible ICUs within Australia and New Zealand. Survey responses were available from 54/180 ICUs. The majority (71%) were located within metropolitan areas and categorised as a tertiary level ICU (50%). The mean number of nurses employed per ICU bed was 4.7 in Australia and 4.2 in New Zealand, with 69% (IQR: 47-80%) of nurses holding a postgraduate specialty qualification. All units reported a 1:1 nurse-to-patient ratio for ventilated patients with 71% reporting a 1:2 nurse-to-patient ratio for non- ventilated patients. Key ventilator decisions, including assessment of weaning and extubation readiness, were reported as predominantly made by nurses and doctors in collaboration. Overall, nurses described high levels of autonomy and influence in ventilator decision-making. Decisions to change ventilator settings, including FiO(2) (91%, 95% CI: 80-97), ventilator rate (65%, 95% CI: 51-77) and pressure support adjustment (57%, 95% CI: 43-71), were made independently by nurses. The authors conclude that the results of the survey suggest that, within the Australian and New Zealand context, nurses participate actively in ventilation and weaning decisions. In addition, they suggest, the results support an association between the education profile and skill-mix of nurses and the level of collaborative practice in ICU.