Background: Delirium is considered a common, life threatening and a cause of morbidity and mortality that can be prevented in ICU patients. Undetected and untreated delirium is a catalyst to increase mortality, morbidity, functional decline and result in increasing requirement for nursing care, healthcare expense and hospital length of stay. Several studies have indicated that nurses' knowledge and practices for delirium are inadequate. Therefore, the aim of this study is to assess nurses' knowledge, and practices about delirium at the ICU of the Emergency Hospital, Mansoura University. Subjects and Methods: A descriptive exploratory design was used to carry out this research on fifty four nurses who are involved in providing direct care for ICU patients in Emergency Hospital, Mansoura University. Two tools were used to collect data: the knowledge evaluation sheet and observational checklist. Results: the findings showed that knowledge and practices for majority of studied nurses were unsatisfactory regarding delirium and there is no correlation between nurses' knowledge and practices scores. Conclusion: there is need for continuing education to upgrade nurses' knowledge and improve their practical skills regarding delirium. Recommendations: enrichment of nurses' knowledge and practices related to delirium to be the corner stone in care of ICU patients. As well, replication of this study on large probability sample.