Abstract: Methanolic extract of Macaranga barteri Mull-Arg (Euphorbiaceae) was investigated for antioxidant properties using different in vitro tests, including DPPH free radical scavenging, reducing, inhibition of linoleic acid lipid peroxidation, iron chelating power. The total phenolic content was also determined and expressed in gallic acid equivalent. The antioxidant activities increased with increasing concentration of the extract to certain extent then level off with further increase. The radical scavenging activity of the extract was comparable to that of BHT and ascorbic acid and no significant difference between them (p>0.05). The extract of M. barteri showed strong inhibition of lipid peroxidation in linoleic acid system and moderate reducing properties. It demonstrated poor iron chelating capacity compared to EDTA used as positive control, suggesting metal chelation plays very little role in antioxidant properties of the extract. This study showed that the leaf extract of M. barteri is a potential source of antioxidants.