Medication administration should be an error-free process as possible. Critical care nurse need to be diligent in discouraging interruptions to prevent harm to the patients who are being cared for. Medication administration errors are a constant occurrence on the unit, and patient safety must be a focus. Aim: to assess nurse's knowledge and practice regarding medication errors in critical care units. Design:   Descriptive exploratory design was utilized to conduct the current study. Settings: The study was conducted in  the following critical care units affiliated to Al minia University Hospital ; Intensive care, neurosurgical care, cardiac care, chest care and finally stroke unit. Sampling: A convenient sample consisted of 60 nurses was obtained from previously mentioned settings regardless of their personal characteristics. Tools: Two tools were used; First; A structural interviewing questionnaire to collect demographic data of the studied nurses and their knowledge regarding medication administration errors. Second; medication administration checklist to assess nurses' practice concerning medication administration errors. Results: The study findings showed that nurse's mean knowledge (Mean+SD =10.7+2.29) and practice (Mean+SD = 23.1+4.58) scores were unsatisfactory regarding medication administration errors. Moreover, no significant differences were found among them by them regarding demographic characteristics' Conclusion: the mean nurse's knowledge and practice were low.  Recommendations: The study recommended implementation of comprehensive, interactive, and continuous educational programs regarding drug administration errors