Antioxidant activity [as measured by oxidation radical absorbance capacity (ORAC) assay], total anthocyanins, total phenolics, and quercetin were measured on frozen, fully-mature fruit of 13 and 15 blackberry (Rubus subgenus Rubus Watson) genotypes in 1999 and 2000, respectively. Additionally, in 1999, ellagic acid was measured. Eight genotypes were common among sample years. The highest ORAC value was for 'Kiowa' (67.9 mmol Trolox equivalents/g of whole fruit) in 2000. Next highest was 'Navaho' which had a two-year average of 48.8. The lowest activity was for selection APF-12, 17.3. Total anthocyanins ranged from a high of 3630.9 mg/kg (malvidin-3-glucoside equivalents) for 'Kiowa' in 2000 to 720.6 for APF-12 for the same year. Total soluble phenolics were highest for APF-12, 10,580.8 mg/kg (chlorogenic acid equivalents) in 2000 to 4217.6 for 'Choctaw' in 1999. Quercetin levels ranged from 94.3 mg/kg fresh weight for 'Arapaho' in 2000 to 10.2 for 'Shawnee' in 2000. Ellagic acid ranged from a high of 383.8 mg/kg fresh weight for 'Chickasaw' to 121.0 for 'Kiowa'. Research continues to further characterize genotypic and year-to-year variation for these health-promoting compounds.