Breast tumor diseases, either benign or malignant, represent big health issue. Benign breast tumors most often occur in women of younger age, they can appear even in their adolescent years. Malignant breast tumors are most often in women over 50 years old, even though malignant breast tumors are more and more common at a younger age. It is necessary to educate women about the importance of a breast self exam in order to notice first symptoms in time. This paper is composed of several chapters describing the anatomy and physiology of the breast, pathological changes of breast tumors and critical factors for the development of the disease. The work covers the classification of breast tumors, that is stages of the disease, and the process of diagnosing and treating diseases together with nursing care of the patient before and after breast surgery. The paper presents a study that presented data on the frequency of breast tumors in General hospital Pula. In addition to the number of patients in the last 10 years, the surgical procedures that were used to treat people suffering from breast tumor diseases are also presented.