English abstract Background: Educational guidelines after bone marrow transplantation provide patients with sufficient knowledge and practices to reduce expected complications. Aim: This study aimed to determine the effect of educational guidelines on patients’ knowledge and practices regarding complications post-bone marrow transplantation. Research design: A quasi-experimental design was utilized to achieve the aim of this study. Setting: The study was conducted at Oncology Center affiliated with Mansoura University,Egypt. Subject: A convenient sample that included (50) patients post bone marrow transplantation. Tools:(I) Patient’s assessment sheet, (II) Patient’s knowledge, and III: Patient’s reported practices (pre and post .Results: This study revealed that there was a statistically significant improvement in patients' knowledge and reported practices respectively pre and post-educational guidelines. There was a positive correlation between knowledge and practice at pre, post, and follow-up implementation of the educational guidelines regarding complications post bone marrow transplantation. Conclusion: The current study concluded that educational guidelines regarding complications post-bone marrow transplantation have a positive effect on improving patients' knowledge and reported practices. Recommendation: Provide continuous educational guidelines regarding complications post-bone marrow transplantation. Keywords: Complications post bone marrow transplantation, educational guidelines, knowledge, and practices