Background: As in vivo models such as animal and human tests have many potential problems the keratinocyte culture model has previously been used as an in vitro model for testing skin irritancy for common skin irritants. Objective : To determine the skin irritant potency of several solvents, we employed cultured human keratinocytes as an in vitro model. Methods : To evaluate the cytotoxicity of solvents, the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide(MTT) test, lactic dehydrogenase(LDH) release test, and tritiated thymidine incorporation test were used. Results : Dose dependent decrease of cell viability and DNA synthesis, and dose dependent increase in leakage of LDH liberation were observed in normal cultured human keratinocytes after exposure to several solvents. The cytotoxicity potency of several solvents measured by each method were slightly different. Conclusion : These observations suggest that the cultured human keratinocyte model would be useful in evaluating the cytotoxicity of solvents. (Kor J Dermatol 1996;34(1): 58~63)