Background: Breast cancer is the most common form of cancer among women Worldwide. It is becoming a major health problem in many developing countries such as Ethiopia currently Quality of Life is emerging as an important health outcome which requires to be incorporated in the holistic management of patients. there are few studies conducted in Ethiopia that have investigated QoL among breast cancer survivors. Objective: To assess health related quality of life of women who undergone mastectomy for breast cancer Methods: This study was an institutional based cross-sectional research conducted on 198 breast cancer patients from October to November, 202020. European organization for research and treatment of cancer QoL questionnaires QLQ-C30 (Quality of Life Questionnaire-Cancer 30) and QLQ-BR23 (Quality of Life Questionnaire- Breast Cancer 23) were used to measure the quality of life. The data entered, cleaned and analyzed By SPSS 23 version software. Results: Study participants had a global health status/ QoL scale mean of 57.95 and SD=11.35. They have a functional scale score ranging from a mean of 38.2 (SD=13.46) fore physical functioning to a mean of 50.84 (SD=21.2). all symptom score means are above 50. On BR23 functioning scale/item all mean scores are below 50. On the other hand br23 symptom scales mean score range from 54.7(SD=20.5) for upset by hair loss to 60.8 (SD=15.7) for arm symptoms. Conclusion: Our patients reported poor quality of life as it is compared to many study findings so that there should be focus on improving QoL by holistic approach of treatment. Key words: quality of life, breast cancer