In recent years, the increase in incidence of malignant tumours of breast has been observed in Poland. Every year approximately 10 thousands of new cases of breast cancer are registered. 19 per cent of all women afflicted with malignant neoplasms suffer from breast cancer. According to considerable experience of the western countries, prophylaxis combined with screening examinations is the most effective and, also, the cheapest method of fighting against neoplasm. In the face of steadily growing danger, which affects more and more women, an attempt to assess the knowledge and behaviour towards prophylaxis of breast cancer among women over 35 was made. The researches, carried out between April and November 2002, were conducted with the use of our own questionnaire basing upon literature on the subject. The poll was intended for women aged between 35 and 60. The group of 300 women, who live in the south-east part of Poland, was surveyed. A detailed analysis of the data revealed that almost 50 per cent of women know the rules of preventive actions in the spheres of breast self-control and mammography. The level of knowledge of primary prophylaxis correlates with the level of education of women. The higher is education, the greater is knowledge about the risk factors of breast cancer. The highly educated women more often and more systematic take preventive actions leading to early detection of breast cancer. The women in the 35-45 age group more regularly and more often perform monthly breast self-control. Also the fact of the prevalence of breast cancer in the members of the polled women's families raises the discipline of performed examination.