Research within the past decade has provided compelling evidence that anaesthetics can act directly as allosteric modulators of transmitter-gated ion channels. Recent comparative studies of the effects of general anaesthetics across a structurally homologous family of inhibitory amino acid receptors that includes mammalian GABAA, glycine and Drosophila RDL GABA receptors have provided new insights into the structural basis of anaesthetic action at transmitter-gated channels. In this article, the differential effects of general anaesthetics across inhibitory amino acid receptors and the potential relevance of such actions to general anaesthesia will be discussed.