Background: Hemodialysis is a safe life procedure. On other hand, it causes threatening complication, which can lead to mortality and morbidity .So, nursing guideline is one of approach that help to improve hemodialysis nurse's knowledge and practice which decrease the risk of hemodialysis complications. Aim: assess the effect of applying nursing guidelines on nurses' knowledge and practice at hemodialysis units. Method: A quasi-experimental design was adopted. Setting: The study was carried out at the Mansoura University Hospital hemodialysis unit. Subject: A purposive sample of fifty nurses of both male and female who affiliated to hemodialysis units and cared for patients undergoing hemodialysis. Tools: There were two tools used; Tool I: Structured Interview Questionnaire and, Tool II: Observational Practice Checklist. Results: Finding revealed that there was positive effect in knowledge and practice level post applying nursing guidelines comparing with pre applying nursing guidelines. Conclusion: Study concluded that nurses' knowledge and practice have been successfully improved post applying nursing guidelines. Recommendations: Provide periodically evaluate nurses' knowledge and practice to find out what training programs are necessary