Aim To determine cholesterol and cholesteryl ester of U937 monocyte within it's foaming procedure,and to obtained a simple and useful method to identify foamcell.Methods Cholesterol and cholesteryl ester was ex-tracted from U937 monocyte by hexane-isopropanol,and it's triglycerides was hydrolyzed by ethanolic KOH,and it's protein contents was removed by trichloroacetic acid.Father separation of cholesterol and cholesteryl ester was accompolished by high per-formance liquid chromatography(HPLC),using an eluent of isopropanol-n-heptane-acetonitrice and a Gen-Pak FAX column(with a little hydrophobic prop-erty,using for nucleic acid separation)and it's choles-terol peak was identified by L-B(Lieberman burchard)reaction and spectrum index analysis.Results Cholesterol concentration has a high linear relationship with it's peak area within 0.05-1.0g/L,the limits of detection of cholesterol is 4mg/g cell pro-tein(100mg cell protein equivalent to 1×108 cells).The cholestelyl ester inside U937 amount to 62% to total cholesterol after cholesterol-loaded for 48 hour.Conclusion This method is useful and simple to i-dentify foam cell.