Consumption of food products with higher antioxidant concentration has shown potential to contribute to enhanced human health. Understanding genetic and environmental effects on antioxidant activity in winter wheat (Triticum aestivum L.) would assist in genetic improvement. Our objectives were to i) characterize the genotypic, environment (E), and G x E effects on antioxidant properties in hard winter wheat and ii) estimate associations between antioxidant properties and other end-use quality traits. Twenty-four hard winter wheat genotypes were grown in 2003-2004 at two rainfed and two irrigated locations in Colorado. Samples were milled on a Brabender Quadromat Senior mill to obtain bran samples. Total phenolic content (TPC) and antioxidant activity using the 2,2'-azinobis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) method were determined. L-Dopa polyphenol oxidase (PPO) and grain protein concentration (PRO) were estimated from whole grain samples. Highly significant (P<0.001) variation was observed among genotypes and environments for ABTS, TPC, PPO, and PRO. The GxE interaction effects were also highly significant for ABTS, TPC, and PRO. ABTS values ranged from 10.92 to 24.99 µmol trolox equivalent antioxidant capacity (TEAC) per gram dry bran, with entries from the irrigated environments having higher ABTS values than samples from rainfed environments. TPC ranged from 1.35 to 1.98 mg gallic acid equivalents (GAE) per gram dry bran with genotype averages at one irrigated location approximately 25% higher than at the other three locations. Averaged across the two irrigated environments, TPC was positively correlated with ABTS (r=0.81) and negatively correlated with PRO (r=-0.68), while ABTS was negatively correlated with PRO (r=-0.51). Similarly, averaged across the rainfed environments, TPC was positively correlated with ABTS (r =.25) and ABTS was negatively correlated with both PPO (r=-0.25) and PRO (r=-0.40). Several genotypes with high average ABTS and TPC were identified and may prove useful in breeding for antioxidant enhancement in wheat.