Background: Inula japonica Thunb. is a plant belonging to the family compositae. Inulae flos (flower of I. britannica var. chinensis Regal.) is the dried flower of I. japonica Thunb. and contains various flavonoids (patulitrin, nepitrin and kaempferol), which have been utilized in traditional oriental medicine to treat nausea, phlegm, and coughs. However, ethanol extract of I. britannica (IJE) has not been previously studied for its use in cancer treatment, and its effects on oxidative stress, or inflammation. Thus, the present study investigated the anti-oxidant, anti-inflammatory, and anti-colorectal cancer effects of IJE using RAW264.7 and HCT- 116 cells, which are human colorectal cancer cell line. Methods and Results: IJE contained flavonoids (80.95 ± 5.3 ㎎/g) and polyphenols (310.53 ± 10.6 ㎎/g). Moreover, it reduced lipopolysaccharide (LPS)-induced nitric oxide (NO) production and H2O2-induced oxidative stress by decreasing reactive oxygen species (ROS) levels. Additionally, the 500 ㎍/㎖ IJE treatment increased caspase-3 activity and apoptotic cell death in HCT-116 cells. Conclusions: These results demonstrate that the anti-cancer effect of IJE against human colorectal cancer cells involves caspase-3 activation and apoptotic cell death. IJE also inhibited LPS-induced NO production, and H2O2-induced oxidative stress in RAW264.7 cells. However, further studies are required to explore how IJE treatment regulates signal transduction in NO and ROS production.