Background: Breast cancer is the most common type of cancer in Egyptian women and although incidence rates are not as high as in the west, yet breast cancer mortality is considerably worse. The nurse plays a critical role in the early detection and prevention of breast cancer. Aim of the study: To assess factors associated with delayed diagnosis of woman breast cancer. Research design: A descriptive exploratory research design. Sample: Purposive sample of 100 women diagnosed with late-stage of breast cancer. Setting: The study was carried out in the surgical inpatient ward and outpatient clinic, chemotherapy and radiation inpatient therapy wards at Aswan oncology cancer institute. Tools of data collection: Structured interview sheet developed by researchers and had two tools, First Tool: covered 2 parts: 1st part: Sociodemographic characteristics; 2nd part: Medical history, Second Toolcovered by 2 parts 1st part Knowledge about risk factor and screening test of breast cancer.: 2nd part factors related to women and health care system delay. Study Duration: During the period of four months from the beginning of February 2018 to the end of Mai 2018. Results: The study results revealed that the most common factors that delay diagnosis of breast cancer were lack of awareness of breast cancer (95%), fear of disease & treatment adverse effects (53%). Also, statistically a highly significant (P<0.000) was found between the level of education with delay diagnosis with a high percentage in illiterate patients delay more than 6 months (92.1%).Conclusion: Delay in breast cancer diagnosis was influenced by interactions between many factors as lack of awareness about disease and methods of early detection, fear of disease & treatment adverse effects, and long-distance to a health care center. Recommendations: Educational program is needed to increase females' awareness and knowledge about disease and screening test of early detection.