[摘要]:Background: Despite advances in treatment, recurrent breast cancer remains a lethal disease. The epidermal growth factor receptor family has been suggested to play a role in breast cancer. However, no investigations of the frequency of EGFR mutation and the potential role of EGFR tyrosine kinase inhibitor (TKI) in Japanese patients with breast cancer. Materials and Methods: Tumor specimens were collected from 84 breast cancer patients who underwent surgery. Polymerase chain reaction-based methods were used to examine EGFR-activating mutations (exon 19 and 21). Results: Activating mutations in the tyrosine kinase domain of EGER were not identified in any of the tumors. Conclusion: EGFR-activating mutations were not present in the Japanese breast cancer series studied here. Therefore, unlike lung cancer, EGER tyrosine kinase inhibitors are unlikely to provide any benefit for Japanese breast cancer patients.