Abstract: Objective To study the effect of high temperature combined with endotoxin on the apoptosis of RAW 264.7 cell.Methods The cultured RAW 264.7 cells in vitro were divided into 4 groups:normal temperature(37℃) blank,high temperature(40℃) blank,37℃+lipopoly saccharide(LPS),and 40℃+LPS guoup.After 3 and 24 hours culture under the condition of 95% O₂ and 5% CO₂,we detected the apoptoisis rate of RAW 264.7 cells with flow cytometry.Results Apoptosis rates were extremely low in 37℃ blank group(both 3hr and 24hr),as well as in 37℃+LPS group.The high temperature(40℃) groups,on the other hand,showed higher possibilities of cell apoptosis.Compared with 37℃+LPS goups,40℃+LPS group showed a much more obvious tendency of cell apoptosis(P < 0.05).But there was no significant difference(P > 0.05) between the apoptosis rate of 40℃ blank group and that of 37℃ group.As time passed by,the rate of cell apoptosis increased markedly (P < 0.05).Conclusion High temperature combined with endotoxin plays an importantrole in the apoptosis of RAW 264.7 cell.And the severity of cell apoptosis rises significantly with the extension of exposure tmie.