Matrix metalloproteinase-9 (MMP-9) degrades type IV collagen constituting the major structural component of the basement membrane and extra cellular membrane. The enzymatic activity is found to be elevated in tumor tissues. With the aim of finding novel MMP-9 inhibitors from natural products, 87 extracts of oriental medicinal herbs, which are used as prescriptions for cancer treatment in traditional Korean medicine, were screened for their inhibitory activities towards MMP-9. It was found that most of the hexane and chloroform fractions as well as water extracts showed a weak inhibitory effect on MMP-9 activity at a concentration of 100mug/ml. However, a strong inhibition was found in the butanol fractions of Cinnamomum cassia PRESL, Magnolia obovata THUEB., Magnolia officinalis REHD. et WILS., Magnolia officinalis REHD. et WILS. var. biloba REHD. et WILS., and Euonymus alatus (THUNB.) SIEB. with inhibitory activity (>90%) at a concentration of 100 microg/ml.