In this study, based on gene expression profiles and immunohistochemistry analyses of breast cancer specimens, we showed that RNF208 was specifically underexpressed in human TNBC cells and in primary TNBC tissues compared to luminal subtype tissues; reduced expression of RNF208 resulted in the decreased recurrence-free survival of breast cancer patients, suggesting that aberrant expression of RNF208 was strongly associated with poor clinical outcomes. Here, RNF208 is linked to breast cancer.