Breasts cancer is an important issue in all women's life, not just in current life but also was in the past and is in the future. It is a threat for many people females and males. But it affect females more frequency than male. It is well Known that female breast cancer incidence is the largest in proportion among other type of cancers in general; where the annual breast cancer achieves the largest proportion among cancers. In this paper the design of the proposed Rule Based System will be presented and the symptoms of the breast cancer disease and possible ways to prevent it will be outlined. The proposed Rule Based System was produced to help people to Prevent and early detection breast cancer, because it is known that this disease does not have medication or cure yet. SL5 Object language was used in the designing of the proposed ruled based system.