cancer related lymphedema is a serious clinical problem, associated with high rates of morbidity, mortality, prolonged hospital stay and increasing medical treatment costs. Aim: To evaluate the effect of designated nursing intervention program on the severity of lymphedema among patients with breast cancer surgery. Design: A quasi experimental design was utilized for data collection. Setting: This study was carried out in surgical and outpatient unit in Fayoum University Hospital. Sample: A purposive sample composed of 80 adult patients who were randomly and alternatively divided into two equal groups. Tools of data collection: Interview Patient’s assessment sheet, knowledge assessment questionnaire, patient’s practices observational checklist, lymph edema tracking assessment tool and upper arm functional index assessment tool. Results: The study revealed that there was a significant difference in knowledge, self-care practice and performance of exercises and lymphedema severity among study groups. Conclusion: The application of designated nursing intervention program is effective on reducing the severity of lymphedema among breast cancer patients. Recommendation: Designated nursing intervention program should be added to routine nursing care delivered to post-operative breast cancer patients.