Introduction: Notch signaling evolves as an important mediator of stem cell biology, tumor formation, angiogenesis and cell fate decisions. Four Notch receptors and five ligands have been identified in human, and they regulate a complex signal transduction pathway that interacts with other stem cell-related pathways as Sonic Hedgehog and Wnt. Recently, dysregulation of Notch pathway has been found to play a crucial role in breast cancer oncogenesis and it could serve as a target for treatment. Methods: We estimated the expression of Notch receptors? at the mRNA level, in 200 human breast cancer samples from a single institution in Northern Greece. Notch 1-4 mRNA was estimated by using Real-time PCR and we correlated the level of Notch expression with breast cancer pathology (TNM, grade oestrogen and progesterone receptors and HER2). Results: We found that Notch receptors (at the mRNA level) are differentially expressed in breast cancer subgroups. Hormone receptor positive cancers express Notch-4 whilst Notch-1 and Notch-3 receptors are involved in the development of triple-negative breast cancer. HER2-positive cancers express lower levels of Notch-1, a finding that is in concert with other reports as well. Conclusion: Notch receptors are expressed differentially and could serve as potential targets for treatment in different molecular subtypes of breast cancer.