P>Aim. This paper is a report of a study exploring the role and practice of nurse anaesthetists, with particular attention to describing how it is 'nursing'. Background. In many countries, there is no nurse anaesthetist role. Recent events suggest that hesitancy about the role may be changing in Canada. Yet, there is limited understanding in Canada about nurse anaesthesia, and many nurses do not believe it is nursing. Method. This grounded theory study involved theoretical and purposive sampling to gather data through: (i) participant observation and face-to-face interviews at the 75th annual American Association of Nurse Anesthetists convention in August, 2006, (ii) follow-up telephone interviews and (iii) a 4-day site visit to a small city in the west of the United States to observe anaesthetists in practice and working with students, visit an educational program, and conduct further interviews. Data collection and analysis were iterative and continued until saturation was reached in December, 2007. Findings. A basic social process of how nurse anaesthetists practise, Keeping Vigil over the Patient, was identified. Keeping Vigil over the Patient is comprised of four categories: Engaging with the Patient, Finessing the Human-Technology Interface, Massaging the Message and Foregrounding Nursing. Conclusion. Nursing was clearly evident in anaesthesia practice, reflecting a seamless integration of divergent ontological perspectives. Based on this examination, this role has considerable potential as a new advanced practice nursing role in countries where it has not yet been adopted.