Background:The patient safety is a fundamental principle of health care. It has been defined as reduction of risk of unnecessary harm associated with delivery of health care to a minimum as well as the prevention of errors and avoidable adverse events, to protect patients from injury. Aim: This study was conducted to assess nurses' performance regarding patient safety in operating room. Design: A descriptive research design was utilized to meet the aim of the study. Setting: The study was carried out in the General operating rooms at Zagazig University hospitals. Study subject: A Purposive sample included all available nurses working in general operating room, (50 nurses)at zagazig university hospital and agree to participate were recruited in this study. Tools: three tools were used including:-I-Self-administered questionnaire. II-Nurses' level of practice observational checklist. III-Nurses' attitude Likert scale. Results: 74% of studied nurses under the study had unsatisfactory level of knowledge regarding patient safety in operating room, 54% of studied nurses had unsatisfactory level of practice regarding patient safety in operating room and 96% of studied nurses had positive attitude regarding patient safety in operating room. Conclusion: about three quarters of studied nurses had unsatisfactory level of knowledge regarding patient safety in operating room. More than half of studied nurses had unsatisfactory level of practice regarding patient safety in operating room. While, the most of studied nurses had a positive attitude regarding patient safety in operating room. Recommendations: On-going and regular in-service educational programs regarding evidence-based guidelines about application of patient safety checklist in the operating room.