The growing interest in the field of biological membranes in recent years is documented by the very large number of articles, reviews, journals and books which are appearing in this field. Why then now a manual on "Membrane Proteins"? The answer is multifold. The protocols which were distributes by the teachers and lecturers at the FEBS-SKMB Course organized in Bern appeared to be very useful not only during the Course to correctly perform the experi­ ments, but also for the future benefit of other students and other curses. To us they appeared very modern and of simple execution, ideal for a Uni­ versity Advanced Course, a Summer School, or similar scientific initiatives. The possibility was also foreseen that such a manual could be used by pro­ fessional scientists, although not initiated into the problems, assumptions and intricacies of biochemical methodology. There are also many research teams who study proteins, for example of human fluids, and who will certainly be interested in the application of new but simply described methods. At the same time we present the student with some more complicated physical techniques which are, however, simply described and easy to execute.