In the present paper we examined the effects of the aqueous extract from Rhizoma notopterygii (RN-ext) on picryl chloride-induced contact sensitivity (PCl-CS). The extract, administered during either induction or effector phase showed a significant inhibition on the ear swelling in mice with PCl-CS. By using the isolated spleen cells from the mice with PCl-CS, we demonstrated the inhibitory effects of RN-ext on matrix metalloproteinase-2 (MMP-2) and MMP-9 activities. However, such inhibition was not found in those from normal mice. The inhibitory effects on MMP-2 and MMP-9 of RN-ext were also observed when it was administered in vivo. In addition, the extract significantly inhibited the migration of spleen cells from PCl-CS mice in transwell system without affecting the cell adhesion to fibronectin. These results suggest that RN-ext exerts its inhibitory activity on the contact sensitivity through decreasing the localization to the inflammation site via down-regulating MMP activities.