Tracazolate (ICI 136,753, 4-butylamino-1-ethyl-6-methyl-1H-pyrazolo[3,4-b]pyridine-5-carboxylic acid ethyl ester) demonstrated dose-related anticonflict activity in rats and mice. The potency of tracazolate appears to be one-quarter to one-half that of chlordiazepoxide. No tolerance to the anticonflict activity of either tracazolate or chlordiazepoxide was evident following 12 consecutive days of treatment. Tracazolate exhibits a much greater separation between sedative and therapeutic doses than does chlordiazepoxide. Furthermore, based on rodent studies, tracazolate should be much less likely than the benzodiazepines to potentiate the actions of barbiturates and ethanol in man. Tracazolate potentiated both the anticonvulsant and anxiolytic effects of chlordiazepoxide in rodents. Unlike benzodiazepines, tracazolate enhances the binding of benzodiazepines to its receptor site. These results suggest that tracazolate is a novel agent with potential clinical utility as an anxiolytic drug.