Taking advantage of GFP transgenic mice, we analyzed the tissue specificity of cell survival in skin grafts. Although GFP causes weak immunore- actions in recipient animals during long-term obser- vation, histological analysis revealed that the ecto- dermal layers including the epidermis, hair follicle, and sebaceous glands of grafted tissues survived in the host tissues. Dermis including nerves and blood vessels of the grafts, however, were partially replaced by host tissues. Our data also raised the possibility that epidermal stem cells in the epidermis play im- portant roles in the successful skin engraftment.