Antioxidant activity, S-allylcysteine (SAC) and total polyphenol contents were measured in aged garlic extract, garlic extract, and garlic.The aged garlic extract had significantly higher 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity, hydrophilic oxygen radical absorbance capacity (H-ORAC), and superoxide anion scavenging activity (SOSA) values than the garlic extract and garlic.SAC and total polyphenol contents showed a strong pos. correlation (r>0.90) with various antioxidant activities.These results suggest that aged garlic extract is a potential functional food with high antioxidant activity due to SAC and polyphenols.