The sampling of gall bladder bile for analytical studies remains an invasive procedure. We demonstrate the application of the non-invasive methodology of (1)H-MR spectroscopy to the qualitative and quantitative assessment of human gall bladder bile in vivo. Spectral profiles in vivo are shown in relation to model and porcine gall bladder bile and the quantitation in man of the trimethylamine (choline) and lecithin concentrations were estimated to range from 25.9 mM to 48.4 mM (mean: 35.8 mM, standard deviation: 9.8). The composition of human gall bladder bile together with the quantitation of various constituents can be studied non-invasively in vivo.