Objective: To investigate the chemical constituents of Viola yedoensis and their antioxidant activity.Method: A systematic isolation was performed by various column chromatography with the n-butanol fraction of the ethanolic extract of the herb. Result: Eleven compounds were isolated and identified as kaempferol-3-O-β-D-sophorosyl-7-O-α-L-rhamnopyrano-side (1)

kaempferol-3

7-di-O-α-L-rhamnopyranoside (2)

apigenin-6

8-di-C-β-D-glucopyranoside (3)

adenosine (4)

esculetin (5)

apigenin-6-C-α-L-arabinopyranosyl-8-C-β-D-xylopyranoside (6)

apigenin-6-C-β-D-glucopyranosyl-8-C-α-L-arabinopyranoside (7)

apigenin-6-C-β-D-glucopyranosyl-8-C-β-D-xylopyranoside (8)

apigenin-6

8-di-C-α-L-arabinopyranoside (9)

apigenin-6-C-β-D-glucopyranosyl-8-C-β-L-arabinopyranoside (10) and kaempferol-3-O-β-D-glucopyranosyl-7-O-α-L-rhamnopy-ranoside (11)

respectively. All compounds were evaluated for antioxidant capacity against DPPH radicals

and compounds 1-5 and 11 showed antioxidant activities. Conclusion: Compound 2 was reported from Viola yedoensis for the first time

and compounds 1 and 8 were the first time to be isolated from the genus Viola.