This qualitative study sought to examine perioperative nursing from the perspective of its practitioners. It was undertaken in two operating theatre sites within NHS Trusts in England. The study used the ethnographic approaches of non-participant observation and semi-structured interviews, with ten observation sessions totalling 85 hours undertaken and eight interviews conducted. Thematic data analysis was undertaken supported by the NVivo qualitative data analysis software program. Two main themes emerged as being core components of perioperative nursing work. The first, ‘Managing Momentum’, related to the work that the nurses undertook to ensure that the operating lists went smoothly and progressed throughout the day. The second, ‘Accounting for Safety’, focussed on the need to ensure that patients were kept safe from harm at all points of their perioperative journey. Three different perioperative nursing roles were identified (anaesthetic, scrub and recovery nurses) and these different types of perioperative nurse undertook managing momentum and accounting for safety work, but each enacted them differently. There was tension between the two components of the work that these nurses had to resolve. The study concludes that perioperative nursing is not a homogenous entity. Nonetheless, perioperative nursing centres on balancing momentum and risk. This insight provides a new understanding of this ‘hidden’ or backstage type of nursing practice. This work will inform perioperative nurses’ understandings of their work, and can also feed into formal definitions of perioperative nursing, recruitment and professional development.