Breast cancer is the most common malignancy and the leading cause of death in women. In Croatia, every eleventh woman is at risk of breast cancer, and a further increase in the number of patients is expected. Women over the age of 50 are most often affected, but there is also an increase of cases of younger women. The causes of breast cancer are not yet fully known, but long-term studies have singled out risk factors that are certainly associated with the development of breast cancer. These include lifestyle, hormonal status, anthropometric characteristics, radiation, and genetic predisposition. Breast cancer is most often detected by breast self-examination. Women should examine their breasts regularly once a month at an early age so that they can notice any changes. In addition to self-examination, women should have regular clinical examinations and mammograms. For the final diagnosis, the specialist may request additional tests. The treatment is very complex, and the best results are achieved by surgical treatment in combination with systemic treatment and radiation. The National Program for Early Detection of Breast Cancer covers all women in the Republic of Croatia aged 50 to 69. As a part of the program, women can have a free mammogram every two years. The goal of the program is to detect cancer at an early stage, and reduce mortality. The aim of this paper is to examine women's knowledge and attitudes about breast cancer prevention. The research was conducted online. A 33-question survey was conducted for the purpose of this research in which a total of 1,063 women participated. The results show that the tendency of self-examination rises with age. In general, the higher the level of education, the more knowledge women have about breast cancer. Women of higher education believe to a lesser extent that women in Croatia are well informed about breast cancer. It was also found that women of different level of education list different reasons of weaker response to mammography. Residents of the city show better knowledge about breast cancer, and a greater tendency to self-examination than residents of the village. It was found that participants who believe that the main reason for the lower response is poor financial situation have less knowledge about breast cancer than participants who believe that the main reason is insufficient information or neglect of health. Women who respond to mammograms also have a higher level of self-examination tendency than women who do not respond. It is very important to educate women about breast cancer and its prevention from an early age, because if cancer is detected at an early stage, treatment is much more successful, survival is longer, and the quality of life is higher.