The effects of natural phytic acid extracted from wheat bran, exogenous phytic acid and ascorbic acid on oxidative stability in chicken o/w emulsion were investigated. The antioxidant activity of phytic acid was evaluated by the TBARS values, oxygen absorption and 2,2-diphenyl-1-picylhydrazyl (DPPH) radical scavenging methods. Phytic acid extracted from wheat bran (PAE) was highly effective in reducing TBARS values (68% of control) and preventing lipid oxidation during oxidation of chicken o/w emulsion at 40ºC. Antioxidant activity of exogenous phytic acid depends on its concentration in chicken o/w emulsion. Ascorbic acid at concentration 0.1% inhibited TBARS formation by 56% of control. Oxygen in the headspace of vials containing emulsion without phytic acid (control) was consumed faster than that with added phytic acid. Assuming a zero time reaction, the rate of oxidation without phytic acid (control) was 0.61% O2/day, while that with phytic acid extract was 0.055% O2/day or about 12 times slower (significantly difference). Phytic acid extract and exogenous phytic acid (4 mM) had more effect on prevention of lipid oxidation as well as oxygen absorption than ascorbic acid and BHA. Radical scavenging activity of phytic acid extract and pure phytic acid (4 mM) were 40.96±0.55 and 40.89±0.32%, respectively. Radical scavenging ability of phytic acid was lower than other common antioxidants (ascorbic acid and BHA). It can be concluded that phytic acid may be substantially inhibited malondialdehyde formation, oxygen uptake, as well as warmed-over flavor development during storage of chicken meat products.