The aim of the present study was to clarify the expression of fibroblast growth factor-inducible 14 (Fn14), a type I transmembrane protein, in breast carcinoma and its correlation with clinicopathological features. We examined the expression of Fn14 in normal breast epithelial cells as well as in breast carcinoma cells, and in 12 cases of breast carcinoma tissues and the paired normal breast tissues by RT-PCR and Western blot analysis. In addition, we analyzed Fn14 protein expression in 171 clinicopathologically characterized breast carcinoma cases by immunohistochemistry. Statistical analyses were applied to test for prognostic and diagnostic associations. The results show that the level of Fn14 mRNA and protein were higher in the cancer cell lines and most cancer tissues than in normal control tissues. Immunohistochemistry showed that Fn14 was expressed in 148 of 171 cases (86.5%). Statistical analysis of cases showed that there was a significant difference of Fn14 expression in patients categorized according to HER-2 expression, lymph node metastasis and clinical stage. Our results suggest that Fn14 protein is a valuable marker of breast carcinoma progression. Fn14 might be used as a valuable prognostic marker for breast carcinoma patients.