Salivary duct carcinoma(SDC) is rare malignancy, accounting for approximately 1-3% of all malignant salivary gland tumors. Systemic chemotherapy has been used for stage IV SDC, but there is no consensus on the standard treatment. SDC is histologically similar to ductal carcinoma of breast and often overexpress HER2/neu, hence HER2/neu targeted therapy could be one of treatment options. A 75-year-old Arabian man was diagnosed as SDC of right parotid gland with extensive metastases. He received oral 5-FU as palliative chemotherapy, but he was intolerable to oral chemotherapy due to severe oral mucositis. Considering immunohistochemical stain of tumor tissue showing strong positive for HER2/neu, we decided to administer an anti-HER2/neu antibody, trastuzumab. Follow-up CT scans before the third dose of trastuzumab demonstrated remarkable regression of multiple metastases as well as primary tumor. This case suggests that HER2/neu targeted therapy may be a potential therapeutic option for the SDC patient with overexpression of HER2/neu.