Abstract: Objective To observe the effects of melagenine extracted from human placenta on the proliferation and differentiation of a melanoblast cell line derived from mouse neural crest cells, NCCmelb4M5, and to elucidate the mechanism of repigmentation in vitiligo following melagenine therapy. Methods MTT method was used to detect the proliferation of NCCmelb4M5 cells. The morphological changes of NCCmelb4M5 cells were observed under an invert microscope, and the expressions of c-kit, tyrosinase and microphthalmia-associated transcription factor （MITF） by RT-PCR. Results The melagenine of 50, 100, and 200 μg/mL could stimulate the proliferation of NCCmelb4M5 cells with an optimal concentration at 100 μg/mL. In the presence of melagenine （50 and 100 μg/mL）, c-kit and tyrosinase began to express in these cells, and MITF expression was increased. Differentiation of NCCmelb4M5 cells from melanoblasts to melanocytes induced by melagenine at 100 μg/mL was observed. Conclusions The melagenine extracted from human placenta can effectively induce the differentiation of NCCmelb4M5 cells from melanoblasts to melanocytes in vitro , which may be a mechanism of repigmentation in vitiligo after melagenine therapy.