: Breast cancer (BC)is the most frequent cancers occurring among women. It is the leading cause of women mortality & morbidity all over the world, among Saudi women there was a significant increase of the incidence of breast malignancy, breast self-examination (BSE) is a simple, very low-cost, non-invasive procedure can be used for early detection of breast cancer at an early stage. The objective of this study is to assess the knowledge & practice knowledge of women in Najran city/ KSA about BSE as a screening method for early detection of BC. A Cross-sectional descriptive study was conducted during 2019 to assess the knowledge and practice of BSE in 449 female samples picked randomly in Najran / KSA. A questionnaire was designed for data collection, SPSS used for data analysis. The finding of this study find that (52.2%) of the study participants between 18-28 years old (72%) completed their education university, 55.5%have good total score knowledge, and 40.3% had practice knowledge's score of BSE and poor total knowledge score about mammogram, there is significant correlation between female knowledge's, practice knowledge's and level of education, while there is no correlation between female knowledge's, practices knowledge's and age group. This study showed that the majority of participants practice breast self-examination (BSE) each month, which contributes to increasing awareness of what is normal for the breasts, the total knowledge score of BSE was excellent and its practice knowledge's too while the relationship between them is significant p-value 0.000. Hence, the continuation of frequent community-based awareness programs and training courses is needed so that women awareness and practice will be increased toward BSE, which helps to pick up any abnormal changes in the breasts and look for medical advice promptly..