CCR4 is a chemokine receptor that has a critical role in immune cell trafficking. T-helper type 2 cells (Th2), regulatory T cells (Treg), interluekin-17–producing T-helper cells (Th17), and skin-homing memory T cells express CCR4 on their surface and migrate toward the chemokines CCL17 and CCL22. CCR4, a C-C type chemokine receptor, has previously been focused on its biological function in immunopathogenesis of hematological tumors. To date, relatively little attention has been paid to the role of CCR4 in promoting metastasis of some solid tumors, including gastric cancer. Our group has shown that the lymphocyte-rich gastric cancers tend to be more frequently positive for CCR4, and found a novel role of CCR4 in tumor-induced immunosuppression, indicating various expression profiles of CCR4 in gastric cancer tissues and multifunctional roles of this molecule in gastric cancer progression.