A number of epithelial lineages have been derived from mouse embryonic stem cells during the past decades, but the long lasting culture has never been reported. In this paper, we report when mouse embryonic stem cells were dispersed into small clumps containing approximately 50 to 100 cells and grown on mitotically inactivated mouse embryonic fibroblast feeder layers for up to 10 d to form epithelial-like colonies. Through subsequent cultivation without mouse embryonic fibroblast feeder layers, a serially subcultured keratinocyte-like cell lineage was established under these conditions. Pan cytokeratin, cytokeratin 14, and cytokeratin 18 were observed in these proliferating cells using immunocytochemistry and flow cytometry. E-cadherin, Involucrin, and keratin mRNAs were determined by a semi-quantitative and a quantitative real time reverse transcription-polymerase chain reaction (RT-PCR). These results confirmed the establishment of a keratinocyte-like cell lineage derived from mouse embryonic stem cells. In this paper also, we describe a method by which mouse embryonic stem cells can be differentiated into cells with some characteristics of epidermal keratinocytes and kept these cells in long-term culture. Potential applications of this method are the in vitro differentiation of cells of interest from embryonic stem (ES) cells of mice during embryonic development and the production of genetically modified epidermal keratinocytes that could be used as temporary wound dressing or as carriers of genes of interest in gene therapeutic treatments or better understanding the mechanisms for epithelial differentiation of embryonic stem cells.