The patient undergoing coronary artery bypass graft surgery deserves to have confidence that the professional nurse is knowledgeable, caring, efficient, and effective in providing necessary preoperative care. Proper preparation of the patient and significant others, expertise during the intraoperative phase, and a thorough knowledge base combined with skill and compassion of the nursing staff during the postoperative phase increase the likelihood of a positive outcome for the patient . The aim of the current study was to assess nurse’s knowledge and practices regarding care of mechanical ventilator and chest tube among postoperative CABG patients at Cairo University Hospitals. A descriptive exploratory design was utilized in the current study. A Sample of convenience 40 diploma nurses and B.Sc.N, working in the cardiothoracic ICUs of Cairo University Hospitals were recruited for a period of 6 months constituted the study subjects. Two tools were utilized to collect data for this study namely: Sociodemographic data sheet and nurse’s knowledge assessment sheet about caring of mechanical ventilator and chest tube.