Lepisorus thunbergianus (Kaulf.) Ching has been used in folk medicine in Korea. In this study, a L. thunbergianus methanol extract and its fractions were investigated for their antioxidant properties. The results showed that the ethyl acetate and butanol fractions of L. thunbergianus possess potent DPPH radical scavenging activities. Both fractions also possessed reducing power and inhibited reactive oxygen species formation. In addition, the cytotoxic activity of the L. thunbergianus n-hexane fraction (HF) was investigated. The results suggested that the HF remarkably suppressed proliferation of human breast, liver and colon cancer cells. These results demonstrate, for the first time, that L. thunbergianus extract induces apoptosis in SW620 cells, suggesting that L. thunbergianus may have potential as a therapeutic agent for colon cancer.