Gastric cancer is one of most common types of cancers. Metastatic gastric cancer has a poor prognosis and is accepted as incurable at this stage. Treatment of metastatic gastric cancer did not progress substantially until new targeted agents have come out. Recently published ToGA trial showed promising results in HER2 overexpressing metastatic gastric cancer. In this case we present a case with an excellent complete response with anti-HER2 treatment. Most importantly, we wanted to emphasize (1) the importance of early determination of HER2 overexpression, and (2) to draw attention of anti-HER2 agents in the first line treatment even in patients with a poor performance status.