Background: The initiative of developing safety to assure patients' safe from harm have become central concerns in quality improvement in the healthcare system. Developing and maintaining safety is a principal aspiration of the current patient safety movement, and sustaining a strong safety culture is seen as imperative to the delivery of safe, high quality and cost-effective patient care. Aim of the study: The aim of this study is to assess the nurse's awareness regarding patient safety culture at Mansoura University Hospital. Subjects and Methods: A descriptive comparative design was utilized to attain the aim of the present study. The study sample composed of 102 staff nurse. Data was collected by using the hospital survey of patient safety culture (HSPSC) questionnaire (Aboshaiqah, 2010). Results: more than half of the nurses under study have unawareness of the patient safety culture. There were no statistically significant differences between the awareness of nurses working in medical units and nurses working in surgical units regarding to patient safety culture in all sub dimensions. The majority of the nurses under study did not report the safety events "errors" in their work areas. Number of events written in the last 6 months was very low. Recommendation: It is recommended that Policy makers and leaders should develop acceptable standards for patient safety system. This can be achieved through initiated and supported an effective safety culture assessment among all working nurses, Staff development programs are needed for all nurses to understand the values, beliefs, and norms about what is important in an organization and what attitudes and behaviors related to patient safety are expected and appropriate for achieving a culture of safety.