Background: Breast cancer is an important global public health problem due to its high incidence and mortality. Women's experience of breast cancer is complex, affecting all aspects of life during and after treatment Aim: The Aim of the Study is to evaluate the effect of application of Health Belief Model about Breast Cancer among Women Attended to Outpatients Beni-Suef Specialized Hospital Subjects and method: Research design: A quasi-experimental design was conducted in this study, Sample type:  A convenient sample from of all women attending to the previous setting throughout 3 months, Setting: The study was conducted at all outpatient clinics in Beni-Suef specialized hospital , Tool: three tools was used to collect data., Tool I: Structured interviewing questionnaire and it was consisted of four parts; part I: sociodemographic data of women, part II: obstetrical data of women, part III:  women knowledge, Tool II: Champion's Health Belief Model Scale. Tool III :reported practice of women Results: there was a marked improvement in total women's knowledge as the pretest was (56%-31%-31%) improved to(3%-6%-91%) during posttest, respectively, there were marked improvement in the practice after the implementation of the HBM from one third (33.7%) of the women has satisfactory practice with pretest to (83.70%)with  posttest and vast majority (91%) of the studied women has negative believes toward pre HBM implementation regarding BC which decreased to more than one tenth (13.3%) of them post HBM. Conclusions: The results of present study supported the research hypothesis that there is marked an improvement in knowledge, practice and health beliefs toward breast cancer compared to before application of health belief model. Recommendations: Continuing BC preventive program for women to improve their awareness. Several instructional handout &brochures should be distributed to women containing preventive measures of BC &steps of BSE. More studies on large samples of women are required for prevention &early detection of BC Extensive educational programs about BSE & its techniques for health workers in different medical setting.