Since its first use in humans 50 years ago, electroconvulsive therapy has been a controversial topic. Nevertheless, a great many experimental and clinical data have been collected. Much of it strengthens the notion that ECT is a more specific therapy than it appears at first sight. The pharmacological effects of ECT seem to be directed toward changes in signal transduction chain processes in the synapse and on the postsynaptic cell membrane. Some aspects of this have been well investigated, especially the effects of ECT on membrane receptors, whereas others have only recently evolved. This article discusses some general principles and conclusions and focuses on some very recent data acquired with new laboratory techniques, such as in vivo dialysis and molecular biology. An attempt is made to interpret these new data and to integrate them in previous results.