This volume contains the proceedings of the FEBS Sym posium on the Biochemistry of Membrane Transport, which was held at the Swiss Institute of Technology, Zlirich, July 18-23, 1976. Of the speakers invited or iginally, only five could not attend the meeting, and of the lectures given, all but one of the texts are published here. Thus, this volume gives a faithful ac count of the way the meeting was originally conceived and actually took place. This Symposium on Biochemistry of Membrane Transport was the first Symposium sponsored by the FEBS outside the yearly FEBS-Meetings, after the Special Meeting on Industrial Biochemistry, which took place in Dublin in 1973, and it reflects the interest and the trend for gatherings of smaller size than the official FEBS Meetings. The topic of the Symposium was an easy choice, not only because membrane transport is becom ing more and more important to biochemistry every year, but also because of the long-standing interest of Swiss Science in the field. In the choice of the topics and of the speakers, efforts were made to achieve as balanced a coverage of the area as possible. However, since some aspects of membrane biochemistry were dealt with extensively at the parallel 10th Inter national Congress of Biochemistry in Hamburg, GFR, cer tain topics were given less emphasis than others. The Symposium was attended by about 400 participants (we expected 200-250); among them 48 were invited speakers, and some 200 contributed posters.