Abstract: Objective: To study the localization of effector adoptively transferred natural killer(NK) cells and dendritic cells (DCs) in murine subcutaneously tumor. Methods: B16-F10 melanomacell line was implanted subcutaneously into C57BL/6 mice. NK cells and DCs were prepared and la-beled with Brdu and DAPI. The mice received labeled NK cells and DCs via the vein or located injec-tion. Tumor and other organs were removed at different time points after the adoptive transfer and pro-cessed. The histopathological change of tumors were observed by HE staining. The labeled NK cellsand DCs were obsevered and numbered by use of fluorescense microscope. Results: NK cells and DCsadopted by the vein injection accumulated mostly in tumors and microcirculation of tumor, and thenumber of effector cells was significantly different (P<0.01). By four hours after injection, significantly more cells were seen in the tumor compared with other time points, and by 12 hours after injection, thatwas the least. As in the cases of adoptived by localized injection, infiltrative NK cells and DCs local-ized in the tumors. And the number of the effective cells in different time points was significantly differ-ent (P<0.01). It was the highest in one hour and the lowest in twelve hours after injection. There was asignificantly difference (P<0.01) as adopting different cells, and the number of received NK cells com-bined with DCs was higher than injection of single kind of cells. Conclusions: NK cells and DCs areaccumulated in tumor and those lead to the necrosis or apoptosis of the tumors. NK cells combined withDC are effective immunotherapy in tumor of mouse.