Background: In periodontal therapy enamel matrix derivative (EMD) has been successfully used for tissue regeneration by altering activity of various cells involved in periodontal regeneration. Studies have focused primarily on clinical parameters and outcome. Effects of EMD on oral epithelial cells are of crucial importance in order to understand the biology of regeneration. Aims of this study are to investigate proliferative and cytotoxic effects of EMD on oral epithelial cells and their possible influences on epithelial barrier function. Methods: SCC-25 cells, a human squamous cell carcinoma cell line, and primary keratinocytes were either treated with EMD dissolved in culture medium or added to wells/inserts precoated with EMD. Cells were incubated for 24, 48, and 72 hours. Proliferation rate was analyzed measuring the 5bromo-2'-deoxyuridine nucleotide uptake. Cytotoxic effects of EMD treatment were sampled by lactate dehydrogenase release. Alterations of the epithelial barrier function induced by EMD were investigated by analysis of transepithelial electrical resistance (TER). Results: Statistically significant inhibitory effects of both malignant and primary cell proliferation could be demonstrated by precoating culture plate wells with EMD. No cytotoxic effects caused by EMD were detected. Precoating of inserts with EMD induced a significant increase of TER and barrier function. Conclusions: This investigation compares applying EMD in solution to cells with precoating of wells with EMD. When precoating of wells was used solely, inhibition of cell proliferation was evident. Precoating may represent more suitable clinical usage. Furthermore, prelayering EMD induced an increase of TER of primary cells. These results suggest EMD may enhance barrier function.