The invention describes a process for the determination of the concentration distribution and size distribution of lipoprotein classes in body fluids, e.g. blood. For this purpose, NMR spectra of a sample to be analysed are measured by magnetic field gradient intensities and temperatures under different diffusion-weighted measuring conditions selected according to different pulse programs (e.g. PFG-STE, PFG-LED etc) and consequently in a differentiated manner according to the relaxation times. The different effects of these measuring conditions on the intensity/line form of the NMR signals of the individual lipoprotein classes are determined and permit the determination of a concentration distribution/size distribution of the individual lipoprotein classes.