Background: Abdominal paracentesis is one of the most important treatment methods of cirrhotic ascites. It is very safe, but serious complications may be present if it is performed in an improper technique such as abdominal wall hematoma, hemoperitoneum , bowel perforation and infection. Aim: to assess nurses' performance regarding abdominal paracentasis procedure for critical ill patients. Design: A descriptive exploratory research design. Setting: this study was conducted at medical intensive care unit at the Eldemerdash hospital Affiliated to Ain Shams University. Subjects: All available nurses (51 nurses) working at the previously mentioned setting. Data collection: Tool Self administrated questionnaire it included: Part I: was concerned with demographic characteristics. Part II: was concerned with assessment nurses' level of knowledge regarding abdominal paracentesis procedure. Tool (II): An observational checklist. Tool (III): Nurses' attitude Likert scale. Results: 86.3 % of the studied nurses had unsatisfactory level of total knowledge about the Abdominal Paracentesis Procedure, 74.5% of the studied nurses had unsatisfactory Practices. Additionally 76.5% of the studied nurses had negative attitude regarding paracentesis procedure for critical ill patients,Conclusion Most of the studied nurses had unsatisfactory level of total knowledge, three quarters of them had unsatisfactory level of total practice., less than one quarter of them has a positive attitude regarding paracentesis procedure for critical ill patients. Recommendation: Continuous nursing education and in service training programs should be well organized and equipped with the necessary educational facilities and materials necessary to upgrade the knowledge, practice and attitude of nurses.