The ethyl acetate-soluble fraction of Eucalyptus globulus wood hydrolysates was fractionated on a Sephadex LH-20 column, using methanol as the mobile phase to give four fractions, and both the DPPH (a,a-diphenyl-b-picrylhydrazyl) radical-scavenging activity and composition of raw extracts and isolates were determined. One of the fractions isolated (denoted F4) showed a remarkable anti-oxidant activity (EC50 of 0.15 g/l, in comparison with 0.55 g/l for crude extracts), presenting a comparatively high phenolic content, with ellagic acid as the main component.