The seminar on "The application of NMR techniques on the body composition of live animals", was held on 14 - 15 lune, 1988 at the Bundesforschungsanstalt für Landwirtschaft (FAL), Institut für Tierzucht und Tierverhalten, Mariensee, Germany. This was the third in aseries of meetings organized in the framework of the European Communities (EC) programme for the coordination of agricultural research. The earlier meetings were on "In vivo estimation of body composition", in 1981 in Denmark, and "In vivo measurements of body composition in meat animals", in 1983 in the UK.. The emphasis of the Mariensee meeting on the application of nuclear magnetic resonance techniques benefitted greatly from new equipment just installed at the Institute. Furthermore it was made clear that this type of large-scale facility, which is not readily found elsewhere, could be made available to promote international collaboration in animal science. After discussing the basic principles of the NMR technique and comparing it with alternative, non-destructive methods of body composition analyses, the programme of the Mariensee group was discussed. The obvious advantages of the NMR technique were acknowledged and will clearly have to be weighed against the rather high investment costs for the equipment at present.