The association of exogenous steroid hormones with breast malignancy has long been, and still is, a subject of investigation. This manuscript, as part of a series of articles about effects of exogenous sex hormones on breast conditions, reviews the adverse and beneficial effects of oral contraceptives in various entities separately: benign and malignant breast diseases, women with risk factors of breast cancer, and the general population. Methods: We first reviewed international clinical

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... nes about the subject. Then, a comprehensive search of the literature was carried out using appropriate keywords. Clinical trials, population-based or cohort studies, nested case-control studies, and narrative/systematic reviews were reviewed and relevant data were extracted. Results: Oral contraceptives are contraindicated in women with current or previous breast cancer. Among women at high risk for breast cancer, those with preceding chest wall irradiation should not use pills, while these are allowed in cases with BRCA mutations or with a positive family history of breast cancer. Oral contraceptives may be beneficial for benign breast diseases. For low-risk woman, pills either pose no risk or may induce a very mild risk for breast cancer.Conclusion: Oral contraceptives are generally safe regarding breast diseases except in breast cancer patients or high-risk women, especially those with a history of chest wall irradiation.