This study describes the antioxidant activities and antigenotoxic effects of garlic extracts prepared by different processing methods. Aged-garlic extract (AGE) showed a significantly higher total phenolic content (562.6 +/- 1.92 mg/100 g garlic acid equivalents) than those of raw garlic extract (RGE) or heated garlic extract (HGE). The SC(50) for DPPH RSA in HGE was significantly the highest at 2.1 mg/ml. The SC(50) for SOD-like activity in garlic extracts was, in decreasing order, RGE (7.3 mg/ml) > AGE (8.5 mg/ml) > HGE (9.2 mg /ml). The ED(50) of AGE was the highest (19.3 microg/ml) regarding H2O2 induced DNA damage and its inhibition rate was 70.8%. The ED(50) of RGE for 4-hydroxynonenal (a lipid peroxidation product) induced DNA damage was 38.6 microg/ml, followed by AGE > HGE. Although the heat treatment of garlic tended to decrease the TPC and SOD-like activity and increased DPPH RSA, garlic, in general, has significant antioxidant activity and protective effects against oxidative DNA damage regardless of processing method.