Objectives: The purpose of this study was to investigate the wound healing effect of primary cultured oral mucosal keratinocytes (OMKs) and to assess their roles in skin wounds. Materials and Methods: OMK labeled with BromodeoxyUridine were scattered onto $1.5{ imes}1.5$ cm skin defects of adult female nude mice (OMK group, n=15). For the control, culture media were placed on the wound (control group, n=15). Mice in both groups were sacrificed at three days (n=5), one week (n=5), and two weeks (n=5), and histomorphometric and immunoblot analyses with keratinocyte growth factor (KGF), interleukin (IL)-6, and IL-$1{alpha}$ antibody were performed for the biopsied wound specimen. To verify the effect of the cytokine, rhIL-$1{alpha}$ was applied instead of OMK transplantation, and the OMK and control groups were compared with regard to re-epithelialization. Results: Histomorphometric analyses demonstrated faster re-epithelialization in the graft group than in the control group at the third day, first week, and second week. Newly forming epithelium showed maintenance of the histological character of the skin epithelium. The graft group showed superior expression of KGF, IL-6, and IL-$1{alpha}$ protein, compared with the control group. Similar faster re-epithelialization was observed after treatment with rhIL-$1{alpha}$ instead of OMK transplantation. Conclusion: We successfully confirmed that the graft of primary cultured OMKs promoted regeneration of skin defects. The mechanism of accelerated wound healing by primary cultured OMKs was attributed to inducement of cytokine expression as required for re-epithelialization.