Bone Marrow Aspiration (BMA) is an essential invasive technique for diagnosis, examinations or transplantation. BMA should be carried out by trained individuals who are aware of the indications, contraindications and complications of the procedure. Aim of the study was to evaluate the effect of the designed nursing guidelines on nurses’ performance regarding care of children undergoing bone marrow aspiration. Research design: Quasi-experimental research design was used. Sample: A convenience sample of all available nurses (30) working in Hemato-oncology department at Benha Specialized Pediatric Hospital and purposive sample of 60 children undergoing bone marrow aspiration. Tools: Two tools were utilized. Tool (I): A structured interviewing questionnaire to assess personal characteristics of the studied nurses, characteristics of children and nurses’ knowledge about cancer and bone marrow aspiration. Tool (II): Observational checklist to assess nurses’ practice concerning caring of children with cancer undergoing bone marrow aspiration. Results: There was a highly statistical positive correlation between total knowledge and total practices scores of the studied nurses at pre and post-implementation of designed nursing guidelines. Conclusion: The designed nursing guidelines were effective in improving nurses’ knowledge and enhancing their practices concerning care of children undergoing bone marrow aspiration |