Flos Lonicerae is a medically useful traditional Chinese medicine herb. However, little is known about the antioxidant properties of Flos Lonicerae extracts. Here the antioxidant capacity of water, methanolic and ethanolic extracts prepared from Flos Lonicerae to scavenge 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical and reduce Fe3+ to Fe2+ is examined. Chlorogenic acid, a major component of Flos Lonicerae, is identified and further purified from 70% ethanolic extract with high performance liquid chromatography (HPLC) and its antioxidant capacity is characterized. The total phenolic compounds and chlorogenic acid con-tents in Flos Lonicerae are determined. The present results demonstrate that the Flos Lonicerae extracts exhibit antioxidant ac-tivity and chlorogenic acid is a major contributor to this activity. Flos Lonicerae is a medically useful traditional Chinese medicine herb. However, little is known about the antioxidant properties of Flos Lonicerae extracts. Here the antioxidant capacity of water, methanolic and ethanolic extracts prepared from Flos Lonicerae to scavenge 1,1-diphenyl-2- Picryogenic acid, a major component of Flos Lonicerae, is identified and fully purified from 70% ethanolic extract with high performance liquid chromatography (HPLC) and its antioxidant capacity is characterized. The present results demonstrate that the Flos Lonicerae extracts exhibit antioxidant ac-tivity and chlorogenic acid is a major contributor to this activity.