This experiment was studied about inducers which expected up regulate COX-2 mRNA expression in the HaCaT by using RT-PCR assay. The COX-2 mRNA expression was induced by TPA concentration is 0, 10, 50, 100, 500 and 1000 nM were used. IFN-γ concentration is 0, 10, 50, 100, 250 and 500 ng/ml were used. Also, the level of COX2 mRNA expression was examined at various times such as 0, 15, 30 minutes 1, 2, 4, 8 and 24 hours. For TPA concentration, result of RT-PCR analysis demonstrated that the maximal level of COX2 mRNA was 500 nM TPA (1.1252) at 2 hours and was 100 ng/ml IFN-γ (1.1013) at 30 minute can induce COX-2mRNA expression highest-level. These data demonstrated that both TPA and IFN-γ induces COX2 mRNA expression in HaCaT cell line in a time-and dose dependent manner. This study will be applied for research in the induction and inhibition of HaCaT.