As part of ongoing study focused on the discovery of natural antioxidants from Korean plants by measuring the DPPH (1,1-diphenyl-2-picrylhydrazyl) radical scavenging effect and superoxide quenching activity, methanol extract of Cedrela sinensis (Meliaceae) was found to show potent antioxidant activities. Subsequent activity-guided fractionation of the methanolic extract led to the isolation of four phenolic compounds, (+)-catechin (1), (-)-epicatechin (2), catechin-($4{alpha}{ ightarrow}8$)-catechin (3) and catechin-($4{alpha}{ ightarrow}8$)-epicatechin (4). Their structures were elucidated by spectroscopic studies. These compounds showed the significant antioxidative effects on DPPH. In riboflavin originated superoxide quenching activity, four compounds exhibited the formation of the blue formazan in a dose dependant manner.