The root and rhizomes of Nardostachys chinensis belonging to the family Valerianaceae has been used for medicinal therapy in Korean traditional medicine. The parts have been especially used to elicit stomachic and sedative effects. Our previous studies reported that the water extract of N. chinensis has induced granulocytic differentiation inhuman promyelocytic leukemia (HL-60) cells. The Mitogen-activated protein kinases (MAPKs) are serine/threonine kinases involved in the regulation of various cellular responses, such as cell proliferation, differentiation and apoptosis. In this study, we investigated the signaling pathways on the HL-60 cell differentiation induced by N. chinensis. Activation of extracellular signal-regulated kinase (ERK) increased time-dependently in differentiation of HL-60 cells induced by N. chinersis. Activation of p38 increased slightly at 24 h after N. chinensis treatment, but activation of c-jun N-terminal kinase (JNK) was unaffected. Inhibitor of ERK (PD98059) significantly reduced NBT reduction activity induced by N. chinensis in HL-60 cells. In contrast, p38 inhibitor (SB203580) did not inhibit the cell differentiation. These results indicated that activaiton of ERK may De involved in HL-60 cell differentiation induced by N. chinensis.