Consumption of polyphenol-rich food is associated with decreased risk of oxidative stress-related chronic diseases. Sorghum, a major food and feed cereal crop, has many polyphenol-containing accessions with high antioxidant activity in the grain. However, many of these polyphenol-containing accessions are not high-yielding or food-grade varieties. The natural variation in sorghum grain polyphenols can be used to develop high-yielding, health-promoting specialty food types through marker-assisted breeding. To identify new antioxidant-rich germplasm, we quantified antioxidant activity, total polyphenols, and condensed tannins in whole kernel flour in 266 accessions from the genetically and phenotypically diverse Sorghum Association Panel. Antioxidant activity, total polyphenols, and condensed tannins were in the ranges of 9.6–325.1 μmol of trolox equivalents (TE)/g, 0.8–18.8 g of gallic acid equivalents/kg, and 0–65.5 g of catechin equivalents/kg, respectively. Twenty-three accessions were rich sources of a...