The inhibitory postsynaptic glycine receptor (GlyR) of rat spinal cord is an oligomeric transmembrane protein which forms an agonist-gated anion channel. Expression in Xenopus oocytes of its mol. wt 48,000 subunit generated glycine-gated chloride channels which were analysed by voltage clamp. The agonist and antagonist response properties as well as the desensitization characteristics of these 48 kd subunit receptors resembled GlyRs expressed from spinal cord poly(A)+ RNA. These data indicate that the 48 kd subunit is capable of assembling into a functional receptor homo-oligomer which displays the pharmacology characteristic of the spinal cord GlyR.