Abstract: Objective To study the effect of matrine on ATP binding cassette transporter A1 (ABCA1) expression and cholesterol in monocyte derived foam cells Method The lipid peroxide within cells was measured by TBARS method; The foam cells were examined by oil red O stain. The accumulation of cholesterol in monocyte were measured by fluorescence spectrophotometric method;ABCA1 mRNA and its protein level were determined by RT-PCR and Western blot, respectively. Result In the homonocytes incubated with PMA and low density lipoprotein (LDL), the intracellular accumulated total cholesterol (TC), free cholesterol (FC) , cholesteryl ester (CE) and lipid peroxide increased obviously, and a great percent of foam cells were found by oil red O stain. This was accompanied by a reduction in the membrane content of ABCA1. matrine alter ABCA1 mRNA abundance , indicating that increased ABCA1 transcription , enhanced mRNA level. conclusion The mechanism of anti-artherosclerosis by matrine may be related to reduce cholesterol and to increase the level of ABCA1 expression.