Aim: To describe Australian perioperative nurses' reported frequency and reasons for missed nursing care in the operating room. Design: Cross-sectional online survey conducted in March–April 2022. Methods: A census of Australian perioperative nurses who were members of a national professional body were invited to complete a survey that focussed on their reported frequency of missed nursing care and the reasons for missed nursing care in the operating room using the MISSCare Survey OR. Results: In all, 612 perioperative nurses completed the survey. The perioperative and intraoperative nursing care tasks reported as most frequently missed included time-intensive tasks and communication with multiple surgical team members present. The most frequently reported reasons for missed care were staffing-related (e.g. staff number, skill mix, fatigue and complacency) and affected teamwork. There were no significant differences in the frequency of missed care based on perioperative nurse roles. However, there were statistically significant differences between nurse management, circulating/instrument nurses and recovery room nurses in reasons for missed care. Conclusions: Much of the missed care that occurs in the operating room is related to communication practices and processes, which has implications for patient safety. Implications for the Profession and/or Patient Care: Understanding the types of nursing care tasks being missed and the reasons for this missed care in the operating room may offer nurse managers deeper insights into potential strategies to address this situation. Reporting Method: Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) Statement. Patient or Public Contribution: No patient or public contribution.