Abstract: Objective To investigate the Effects of staphylococcal enterotoxin A (SEA) on the cytotoxicity of T cells stimulated by PML-RARα peptide in vitro. Methods Peripheral blood mononuclear cells from healthy donors were cultured with PML-RARα peptide and SEA for 20 days. After induction,the cytotoxicity of T cells induced against NB4 and K562 cell lines were examined by Cell Counting Kit-8 (CCK-8). The CD4 and CD8 surface markers on the harvested CD3⁺ T cells were detected by flow cytometry (FCM). Results The cytotoxicity of T cells induced by PML-RARα peptide with SEA was higher than that of T cells induced only by PML-RARα peptide against NB4 cells. The FCM assay showed that the ratio of CD4⁺ / CD8⁺ T cells were gradually decreased in both groups of PML-RARα peptide whether with SEA or not at the intervals of day 5, 10 and 20 af ter induction, but the most significantly decreased by PML-RARαpeptide with SEA. Conclusion 　The specific cytotoxicity of CD8⁺ T cells induced by PML-RARαpeptide against NB4 cells could be enhanced with superantigen SEA.