In oral and maxillofacial surgery, there are many cases requiring the graft of epidermal tissues such as maxillectomy, and vestibuloplasty. There have been so many challenges for the culture of the epidermal tissue. Observing the ultrastructure of the cultured human oral kertinocytes, we could compare this findings with that of in vivo ones. With that, we could find the differences and similarities between cultured cells and in vivo ones, and evaluate the clinical applications of cultured tissue. Human gingiva was obtained and the specimen was explanted on 24-well plate. Two types of culture media were used in this culture system. One was for the growth of the keratinocytes (Media I), and the other was for the stratification (Media II). Media I had special ingredients for the epidermal growth; Those were 0.5% dimethyl sulfoxide (DMSO), 30ng/㎖of epidermal growth factor (EGF), 30ng/㎖of cholera toxin, and 5㎍/㎖of transferrin. We cultured the oral keratinocytes for 3 weeks, and at that time the cultured keratinocytes were processed to prepare the specimen for the TEM study. The results were as follows; 1. in the phase contrast micrograph, epidermal outgrowth firstly appeared on the 3rd day after explanation, and the growing keratinocytes were actively mitotic, and had polygonal shape and increased N/C ratio. 2. In the phase contrast micrograph, the outer most cells exhibited areas where broad cytoplasmic processes extended out onto the culture substratum (fan-like appearance). 3. In the TEM micrographs, the cultured keratinocytes showed stratification. The cells were in elongated form, and there were no morphologic differences among the layers usually found in the in vivo gingiva. 4. Most of cellular organelles underwent lysis, and keratohyaline granules were seen. Tonofibrils were dispersed in the cytoplasm. 5. The cells were interconnected by desmosomes, and their frequency of distribution was considered to be lower than that of in vivo keratinocytes. 6. We could conclude the cultured oral keratinocytes exhibited signs of terminal differentiation.