Background: The aim of this study was to determine beliefs concerning breast self-examination in first- and second-degree relatives of patients with breast cancer and evaluate their breast self-examination (BSE) application. Materials and Methods: A survey study was conducted in an oncology polyclinic and general surgery clinic of a hospital in Ankara, the capital of Turkey with a sample of 140 women. Results: It was determined that 60.7% of the participants had conducted BSE and 48.1% had undergone a clinical breast examination. Perceived selfefficacy of the women who performed BSE were significantly higher compared with women who did not practice BSE (p<0.001) Furthermore, perceived barriers were lower among those who had performed BSE (p<0.001). Logistic regression analysis indicated that women who perceived higher self-efficacy (OR: 1.119, 95% CI: 1.056-1.185, p<0.001) and had regular CBE (OR: 8.250, 95% CI: 3.140-21.884, p<0.001) and educational status (OR: 5.287, 95% CI: 1.480-18.880, p<0.01) were more likely to perform BSE. Conclusions: Findings from this study indicated that perceived barriers, perceived self-efficacy, and educational status could be predictors of BSE behavior among the first- and second-degree relatives of patients with breast cancer. Therefore, BSE training programs that emphasize self-efficacy and address perceived barriers are recommended.