Objectives: The aim of this study is to investigate immune enhancing effect of Houttuyniae Herba water extract(HW) on RAW 264.7 cell of mouse macrophages. Methods: Effects of HW on productions of nitric oxide(NO) and hydrogen peroxide($H_2O_2$) in RAW 264.7 mouse macrophages were measured. Effect of HW on production of cytokines such as interleukin(IL)-$1{eta}$, IL-6, and tumor necrosis factor(TNF)-${alpha}$ in RAW 264.7 cells was accessed by a multiplex bead array assay based on xMAP technology. All of results were represented P<0.05 compared to the normal. Results: 1. After 24 hr incubation, HW increased significantly NO production in RAW 264.7 cells at the concentrations of 25, 50, 100 and 200 ${mu}g$/mL. 2. After 24 hr incubation, HW increased significantly hydrogen peroxide production in RAW 264.7 cells at the concentrations of 25, 50, 100 and 200 ${mu}g$/mL. 3. After 24 hr incubation, HW increased significantly IL-$1{eta}$ production in RAW 264.7 cells at the concentrations of 100 and 200 ${mu}g$/mL. 4. After 24 hr incubation, HW increased significantly IL-6 production in RAW 264.7 cells at the concentrations of 100 and 200 ${mu}g$/mL. 5. After 24 hr incubation, HW increased significantly TNF-${alpha}$ production in RAW 264.7 cells at the concentrations of 50, 100, and 200 ${mu}g$/mL. Conclusions: These results suggest that HW has immune enhancing activity related with its increasement of NO, hydrogen peroxide, IL-$1{eta}$, IL-6, and TNF-${alpha}$ in macrophages.