Selection for rapid growth in poultry can be linked to an exaggerated state of oxidative stress (reactive oxidative species). Reactive oxidative species are kept in balance by endogenous and exogenous antioxidants. Two compounds, conjugated linoleic acid (CLA) and berberine a purified compound from plant root extract have been suggested to ameliorate oxidative stress. A six-week study examined the effect of CLA and berberine supplementation on markers of oxidative-stress in poultry. Day old broiler chickens (n=60) were equally divided into six groups; a control, a CLA group where half of the regular oil used in a standard was substituted for a CLA oil mixture, a berberine group consisting of berberine supplementation, an allopurinol group, a CLA and allopurinol with the same dose as the CLA and allopurinol groups and a berberine and allopurinol group. The allopurinol was added to induce an oxidative stress state. Body weight, plasma uric acid, plasma glucose, and relative gene expression of six endogenous liver antioxidants were measured during the course of the study. The addition of allopurinol to the diet induced an oxidative stress state as measured by a significant reduction in plasma uric acid. There were no significant changes in BW and blood glucose concentrations. There was a 10-fold increase in the relative mRNA expression of superoxide dismutase 2 and 3 as well as glutathione peroxidase 1 and 3 in CLA+ALLO and BRB+ALLO treatment groups. Notably, CLA increased the expression of uncoupling protein 19-fold compared to control, while the addition of allopurinol blocked these changes. In contrast, there was a slight increase in the uncoupling protein in the BRB+ALLO treatment. Despite the increase in mRNA expression of the antioxidants genes, these results suggest that at the dosages administered, CLA and berberine were not effective in reversing the oxidative stress induced by allopurinol.