In order to obersve the effect of dexamethasone on the secretion of apolipoproteins AⅠ，AⅡ，CⅢ，B100 and E by cultured HepG2 cells. The apolipoprotiens contents in culture media were measured by radioimmuodiffusion assay (RID) kits developed by authors' research unit. 20-fold lyophilizely condensed culture media were used for the assays.The results showed that dexamethasone can increase the secretion of apoC and E, and inhibit the secretion of apoAⅡ,B100 and CⅢ;and the effect of dexamethasone were strengthened in a dose-dependent manner. When the concentration of dexamethasone was 5.5×10^－5mol/L in the culture media,the secretion of apolipoprotein AⅠand E increased 36.6% and 49.4%（P＜0.01）respectively, while the secretion of apo AⅡ,B100 and CⅢ decreased 38.9%、31.9% and 29.8%（P＜0.01）respectively.