Triglyceride, free cholesterol, and total cholesterol were quantified in lipid extracts of liver and thoracic aorta from nonhuman primates using commercially available enzymatic reagents. Lipids were solubilized in water by the addition of Triton X-100. Results of the enzymatic assays compared favorably with chemical assays of lipids separated by thin-layer chromatography. In addition to saving time, the present method has the advantage of measuring each lipid class from a single sample preparation. Furthermore, the procedure has been adapted for use with microtiter plates that conserve both sample and reagent.