Eph receptor A10 (EphA10) is a valuable breast cancer marker that is highly expressed in breast cancer tissues by comparison with normal breast tissues, as we previously reported. However, the role of EphA10 expression in breast cancer is not well understood. Here, we have analyzed the expression of EphA10 at the mRNA- and protein-level in clinical breast cancer tissues and then evaluated the relationship with clinicopathological parameters for each sample. EphA10 mRNA expression was quantified by real-time polymerase chain reaction using complimentary DNA (cDNA) samples derived from breast cancer patients. Lymph node (LN) metastasis and stage progression were significantly correlated with EphA10 expression at the mRNA level (P = 0.0091 and P = 0.034, respectively). Furthermore, immunohistochemistry (IHC) staining of breast cancer tissue microarrays (TMAs) revealed that EphA10 expression at the protein level was also associated with LN metastasis and stage progression (P = 0.016 and P = 0.011, respectively). These results indicate that EphA10 expression might play a role in tumor progression and metastasis. Our findings will help elucidate the role of EphA10 in clinical breast cancer progression.