An automated method is described for simultaneously determining cholesterol in serum β- and pre-β-lipoprotein fractions. This fast, reproducible, accurate method depends on the ability of β- and pre-β-lipoproteins to form insoluble complexes with polyanionic polysaccharides such as heparin. Values obtained by this method and by similar manual methods described in the literature agree well. This method is extremely useful in mass screening for hyperlipidemias; in certain cases it may be more useful than the determination of only cholesterol or triglycerides.