The purpose of this study is to investigate effects of Anisi stellati Fructus Water Extract on hydrogen peroxide production in RAW 264.7 mouse macrophages. Anisi stellati Fructus were extracted by hot water. Effects of Anisi stellati Fructus water extract (AS) on hydrogen peroxide production in RAW 264.7 were measured by dihydrorhodamine 123 assay after 20, 24, 28, 44, 48, and 52 h incubation at the concentrations of 10, 25, 50, and $100{mu}g/mL$. For 20 h incubation, AS significantly increased hydrogen peroxide production in RAW 264.7 cells by $108.6{pm}1.56%$, $109.5{pm}1.94%$, $108.4{pm}1.14%$, and $107.3{pm}3.06%$ at the concentrations of 10, 25, 50, and $100{mu}g/mL$ (P < 0.05) respectively. For 24, 28, 44, 48, and 52 h incubation, AS also significantly increased hydrogen peroxide production in RAW 264.7 cells at the concentrations of 10, 25, 50, and $100{mu}g/mL$ (P < 0.05). These results suggest that Anisi stellati Fructus has the immune - enhancing property related with its increase of hydrogen peroxide production in macrophages.