Background: Changes in the attitudes and behavior of relatives of breast cancer patients concerning cancer prevention and screening after diagnosis in a loved one were evaluated. Materials and Methods: Forty-three questions were used to collect data from the relatives of the breast cancer patients who had been living with their relatives for at least one year. Results: The study group was composed of 171 female relatives (median age: 43, range: 17-82 yr). After the patients were diagnosed with breast cancer, changes in the attitudes and behavior of their relatives toward the prevention and screening of cancer were evident in 78 (45.6%) of the study participants (e.g. eating habits, quit or reduced smoking, exercise habits). In addition, it was noted that some characteristics of the relatives had different effects on different attitudes and behavior. Conclusions: Awareness on breast cancer among the relatives of breast cancer patients is useful for the management of health and social problems that can be seen in these individuals. At the same time, this information could help countries determine whether their actual level of healthcare for early cancer diagnosis, prevention, and screening are adequate.