The aqueous and methanol extracts of twenty herbs traditionally used in Chinese medicine were screened for anti-HIV-1 integrase activity in a non-radioactive ELISA-based HIV-1 integrase assay. The screening was performed at an herb extract concentration of 50 microg/ml. It was found that most of the aqueous and methanol herb extracts could elicit strong inhibition of HIV-I integrase activity. The inhibition was most likely due to tannins or polyphenolics in the herb extracts. In most of the herb extracts, 40-80% of the anti-HIV-1 integrase activity could be removed after passing through a minicolumn of polyamide resin. After removal of polyphenolic compounds, the methanol extract of Paeonia suffruticosa still exerted potent inhibition of HIV-1 integrase (EC50 = 15 microg/ml) and the aqueous extract of Prunella vulgaris caused moderate inhibition (EC50 = 45 microg/ml). The results support the view that herbs represent a rich source of anti-HIV compounds.