Aim To investigate the effects of macrophage activation on the capacity of apolipoprotein AI to promote cellular cholesterol efflux. Methods 3H labled acetyl low density lipoprotein (ac LDL) was employed as an inducer for foam cell formation by thioglycolate were cultured with apo AI for 18 h, 3 H cholesterol released from cells to the medium was measured by scintillation spectrometry. Results The efflux of cholesterol from inflammatory macrophages to apo AI did not increase markedly with the increase of the concentration of apo AI as that observed in resident macrophages. The macrophage activation resulted in a significantly decrease in the capacity of apo AI (20 mg/L) to promote cellular cholesterol efflux (P<0.01), but had no effect on HDL. Conclusion The macrophages activation may effectively inhibit the capacity of apo AI to remove cholesterol from cells.