Serum lipid,lipoprotein and HDL-c subfractions of Mongolian gerbil were compared by enzymatic method among three different groups. One group fed high lipid diet, the second group fed high lipid diet plus Brucea javanica oil ( rich in unsaturated fat acid ) , and the third group fed basic forage as control. Compared with the control group, the high lipid diet group showed hyperlipemia. The elevation of gerbil's serum cholesterol was asso-ciated with that of LDL-c and HDL-c. The latter contained HDL2-c and HDL3-c. Serum triglyceride was also elevated. The Brucea javanica oil group showed reduced hyperlipemia, compared with the high lipid diet group The reduction of gerbil's serum cholesterol may be caused by the lowering of the cholesterol content in LDL-c and HDL-c. Serum triglyceride was also lowered. The effect is of benefit to antiatherosclerogenesis.