Abstract: Breast cancer is a group of diseases with considerable inner heterogeneity. Intrinsic subtyping has classified breast cancer into major subtypes, such as Luminal A, Luminal B, HER2-enriched, and basal-like breast carcinomas. This classification is based on the specific expression patterns of certain genes that effectively reflect each distinct biology and clinical outcome. Moreover, this classification is widely rev-recd and utilized. Epidemiological studies based on intrinsic subtyping shed a new light on breast cancer recognition. Traditionally validated risk factors showed substantial differences in their association with various intrinsic subtypes. The paradox of risk factors for breast cancer development generally exerting protective effects on patient survival has been observed. This phenomenon is highly likely caused by the heterogeneity among intrinsic subtypes. Future epidemiological studies on breast cancer should develop a further precise basis on the intrinsic subtypes, and this article will summarize the advances in epidemiology based on molecular subtyping of breast cancer.