The MeOH ext., $CH_2Cl_2$ Frac., EtOAc Frac., n-BuOH Frac., and $H_2O$ Frac. of 23 Korean medicinal herbs were prepared and were tested the inhibitory effects on Cytochrome P450 (Cyp) 1A1/2, 2B1/2, 2E1. Among the tested samples, the extracts of Selaginella tamariscina, Euonymus alatus, Salvia miltiorhiza, Angelica acutiloba, Rheum palmatum, Paeonia moutan, Scutellaria barbata, Tribulus terrestris, Hedyotis diffusa, Curcuma zedoaria, Rehmania glutinosa, Trogopterus xanthipes, Melandryum firmum, Achyranthes bidentata, Leonurus sibricus, Panax ginseng, Paeonia lactiflora, Poncirus trifoliata, Cnidium officinale, Cyperus rotundus, Corydalis ternata showed significant inhibitory effects on Cyp 1A1/2, 2B1/2, 2E1. The $IC_{50}$ values of those extracts were found to be below $50;{mu}g/ml$.