The importance of PSIs lies in the fact that they facilitate the recognition of the adverse events and complications which occurred during hospitalization and give the hospitals a chance to improve the possible clinical outcomes. Therefore, the current study aimed at measuring the association between AHRQ PSI03 ( PU rate) and the clinical outcomes including death, readmission within 30 days and the LOS at the cardiothoracic surgery hospital at Ain Shams University. This study will provide the hospital management with baseline data for this type of adverse event and guide them to develop a system for identifying the high-risk group of patients and to upgrade relevant hospital policies and guidelines that lead to improved patient outcomes.