Phase properties of aqueous dispersions of model bile mixtures containing cholesterol, lecithin and bile salts and model mixed lipid digestive mixtures containing cholesterol, fatty acid, monoglyceride, lecithin and bile salts have been characterized by H-2 NMR. We have chemically incorporated a deuteriomethyl (CD3) group into one or two lipid components and utilized differences in motionally-averaged quadrupole splittings (Delta nu) and CD3 chemical shifts, to determine directly by peak-area integration, for a number of compositions on the phase diagram, the distribution of a H-2-labeled component between micellar, lamellar and solid phases, as well as the chemical compositions of these phases. Our data show that increasing cholesterol stabilizes lamellar phases whereas bile salts disrupt them and favor micelle formation.