The genus Taraxacum, known by the common name Dandelion, is a medicinal herb in the family Asteraceae. It has been traditionally used as a folk medicine for the treatment or prevention of various diseases due to its anti-inflammatory and anti-oxidative properties. In this study, we attempted to evaluate protective effects of Dandelion related with anti-oxidative activity to Thioacetamide (TAA)-induced liver damage. 36 rats were randomly assigned to six experimental groups : Control, Dandelion water extract (DWE), TAA, TAA&DWE 300, TAA&DWE 600, TAA&DWE 1,200 groups. Rats in DWE and TAA&DWE groups were pretreated with DWE (300, 600 or 1,200 mg/kg BW) by gavage for 7 days. All rats were treated intraperitoneally with TAA (200 mg/kg BW) or normal saline at 12 hours after last oral administration and sacrificed at 12 hours after last treatment. Levels of WBC and Neutrophil count were significantly decresed in TAA&DWE 1,200 group compared with that in TAA group (P<0.05). In TAA&DWE 600 and TAA&DWE 1,200 groups, serum AST, ALT, GGT levels were lower than TAA group (P<0.05). The serum TG level was significantly elevated in TAA&DWE groups compared with those in TAA group. Liver tissues from TAA group showed extensive histopathological changes, characterized by moderate or severe hepatocytes degeneration, inflammatory cell infiltration, and congestion. In the TAA&DWE group, The severity of histopathological lesions were decreased compared to those in the TAA group. The MDA concentration was significantly decreased and GSH content was significantly increased in the TAA&DWE 1,200 group compared to those in the TAA group. GR, CAT and GST activities in the TAA&DWE 1,200 group were significantly increased compared to those in the TAA group.