This workshop was the second of this series held on the island of santorini in the Cycladic Sea. The first one ("Mechanism of Action of the Nicotinic Acetylcholine Receptor", NATO ASI Se­ ries H, vol. 10) took place in May 1986 and focused on what was at the time the best studied of all neuroreceptors. This second one, held only two years later, demonstrates the im­ mense progress achieved since then in the field of neurorecep­ tors and ion channels. Molecular cloning techniques have now made available the primary structures of a whole array of ion channel proteins, and this in turn has shed light on some gen­ eral principles of the structure-function relationships of these central elements of intercellular communication. The purpose of this workshop was to explore the common ele­ ments in gene and protein structure of already cloned ion channel proteins, and to assess the status of other cloning projects in progress. It explicitly focused on very recently published and unpublished results. All participants kept to these goals thereby demonstrating the very value of such work­ shops for the progress of science.