The water extracts of oriental herbal medicines which have been clinically used to treat bacterial infections in Korea were screened for in vitro antibacterial activity by the paper disc assay method. Two Gram positive bacteria, Staphylococcus aureus SG511, Bacillus subtilis ATCC 6633 and two Gram negative bacteria, Escherichia coli 055, Pseudomonas aeruginosa 9027 were used as test organisms. Among 83 of the extracts tested, 25 were active against Staphylococcus aureus SG511, 9 were active against Bacillus subtilis ATCC 6633, while none showed inhibitory activity against Eschelichia coli 055 and Pseudomonas aeruginosa 9027. Among them, Hwangyonhaedoktang plus hwangyon, Chongwisan, and Ssangbaksan showed remarkably potent antibacterial activity.