Since the first application of gene expression profiling to breast cancer almost a decade ago, the molecular subtyping of breast cancer has advanced rapidly from a novel concept to a clinically valuable prognostic, and possibly predictive, classification. This review summarizes the definition of the basal and related triplenegative subtypes of breast cancer, their clinical associations, and effect on outcome and treatment decision- making. Particular emphasis is placed on the clinical implications of basal breast cancer and potential therapeutic options available to oncologists.