In this study the change of metabolist activity was measured from macrophage to macrophage-derived foam cell by incubating mouse peritoneal macrophages in oxidized Iow density lipoprotein, using tetrazolium dye assay. The resultrevealed that the metabolist activity ascended first,then descended, and the peak was at about 3 hours with macrophage in 5 00 mg/L oxidized low density lipoprotein.