A new analytical procedure for quantifying plasma lipoproteins by proton nuclear magnetic resonance (NMR) spectroscopy has been developed that potentially offers significant advantages over existing clinical methods used for assessing risk of coronary heart disease. Analysis of a single spectrum of a nonfasting plasma sample, acquired simply and rapidly at moderate magnetic field strength (250 MHz), yields a complete profile of lipoprotein concentrations: chylomicrons and very-low-, low-, and high-density lipoproteins. The method is based on curve-fitting (spectral deconvolution) of the plasma methyl lipid resonance envelope, the amplitude and shape of which depend directly on the amplitudes of the superimposed methyl resonances of the lipoprotein components. A linear least-squares curve-fitting algorithm was developed to efficiently extract the signal amplitudes (concentrations) of the lipoproteins from the plasma spectrum. These signal amplitudes correlate well with lipoprotein concentrations determined by triglyceride and cholesterol measurements.