This study explored the possibility that the components in melanoma cytoplasm induce murine BMSCs transformation and expression of Melan-A by morphologically observing the changes of BMSCs and immunocytochemically detecting Melan-A in the cells after culturing BMSCs in medium containing melanoma cytoplasm components (MCC).MCC of B16 melanoma cells was prepared and BMSCs were cultured and induced by adding the MCC into culture medium.The cells were morphologically observed and Melan-A was immunohistochemically detected to confirm BMSCs transformation.MCC-induced BMSCs underwent morphological changes.A number of melanin granules appeared in the cytoplasm of the cells and some were released into surrounding areas.Several cells that might come from one cell formed a cluster,and their granules,together with those secreted by other induced BMSCs,formed a so-called “sphere-formed structure”.The induced BMSCs expressed Melan-A.We are led to conclude that there might be some factors in the cytoplasm of melanoma cells that might induce BMSCs transformation toward melanogenic cell,or even melanoma.