Stem cell therapy is expected to be a promising approach for the compensation of lost organs. The various organization cells that compose an animal's body are always being renewed for the maintenance of homeostasis. The cells that become the source of new cells are a body's own stem cells. Cell therapy, using stem cells, has a few of bioethical problems but there is the advantage that it is not necessary to worry about the immunity rejection of the transplant because the body's stem cell is from it's own body. in our present study we identified side population cells (SP cells), which are highly enriched for stem cell activity in human salivary glands. isolated SP cells expressed high level of DNp63 and PSCA (prostate stem cell antigen), but not nestin, Oct4 and CD34. Real time PCR analysis revealed that the expression of DNp63, detected in immature salivary epithelial cells, gradually decreased through cell differentiation. in contrast, PSCA can be distinguished among early differentiating and later transit-amplifying salivary epithelial cells in tissue culture. Our study suggested that these markers may mark the transition of human salivary epithelial cells. © 2007, The Japan Society for Clinical Immunology. All rights reserved.