Purification and bioassay guided fractionation were employed to isolate compounds with antioxidant activity (AA) from red grape pomace (Vitis labrusca - Bordô variety). The AA was evaluated by in vitro assays: radical scavenging activity (DPPH [1] and ABTS [2]), power reduction of iron (FRAP [3]) and oxygen radical absorption capacity (ORAC [4]). The phenolic compounds were identified using a HPLC-DAD system with a C-18 RP column and mobile phase composed by water and acetonitile acidified with acetic acid and a flow rate of 1 ml/min. A crude extract (CE) was prepared with ethanol:water 50:50 (v/v) in a water bath (50°C) during 45 min [5]. After, the CE was partitioned using solvents in increasing order of polarity: hexane (Fr-Hex), dichloromethane (Fr-CH2Cl2), acetate ethyl (Fr-EtOAc) and ethanol (Fr-EtOH). The phenolic compounds gallic acid, quercetin, catechin, epicatechin, trans-resveratrol, caffeic acid and ferrulic acid were identified in CE and fractions by HPLC. The CE and fractions were evaluated for AA and the Fr-EtOAc has higher activity than CE, while Fr-Hex displayed lowest activity (Table 1).The Fr-EtOAc was separated on open column using silica-gel yielding 97 subfractions (Subfr) that were regrouped into 17 after comparison of similarity in color and Rf by TLC. The Subfr 4, 6 and 8 showed the highest activities (Table 1) and then they were purified by semipreparative HPLC and were collected 12 pure compounds that were analyzed by NMR. These results indicate that the bioguided isolation process was efficient, because it resulted in an increase in antioxidant capacity of fractions and subfractions compared with crude extract.