The moringa (Moringa oleifera Lam.) plant is used as food and as an anti-allergic agent. In this study, we studied the inhibitory effect of moringa root extract on the expression of PMA-induced matrix metalloproteinase-9 (MMP-9), which is the main factor implicated in the invasion and metastasis of cancer cells in MCF-7 cells. At first, various moringa extracts were examined in the MCF-7 cells. Both moringa root extract and leaf extracts inhibited PMA-induced MMP-9 activity, but the root extract suppressed PMA-induced MMP-9 activity to a greater extent than the leaf extract. The moringa root extract also inhibited PMA-induced MMP-9 protein expression and cell invasion. According to RT-PCR, the treatment of the MCF-7 cells with moringa root extract decreased levels of PMA-induced MMP-9 mRNA expression, but not the expression of TIMP-1 and -2, indicating that moringa root extract prevents the transcription of MMP-9 in response to PMA. In addition, moringa root extract specifically suppressed the phosphorylation of ERK/JNK, but not p38. We suggest that moringa root extract abolishes MMP-9 activity/expression through ERK/JNK. In conclusion, moringa root extract suppressed PMA-induced MMP-9 activity/expression by inhibiting the phosphorylation of ERK/JNK in MCF-7 cells. These results indicate that moringa root extract may be a potential antimetastatic and anti-invasive agent. Future clinical research is needed on the anticancer properties of moringa root extract.