The imidazobenzodiazepine, Ro15-4513, which is a partial inverse agonist at brain benzodiazepine receptors, reversed the incoordinating effect of ethanol in mice, as measured on an accelerating Rotarod. This effect was blocked by benzodiazepine receptor antagonists. In contrast, Ro15-4513 had no effect on ethanol-induced hypothermia in mice. However, Ro15-4513 reversed the hypothermic effect of pentobarbital, and, at a higher dose, also reversed the incoordinating effect of pentobarbital in mice. The data support the hypothesis that certain of the pharmacological effects of ethanol are mediated by actions at the GABA-benzodiazepine receptor-coupled chloride channel.