The anticonvulsant BW A78U, tested in a free mouse exploratory situation, reduced in a dose-dependent fashion the locomotion and the number of rearings, this sedative effect being significant up to a dose of 15 mg/kg (IP, 20 min before testing). In an unconditioned conflict test, the light/dark box choice situation, specific for anxiolytics, low doses of BW A78U increased the time spent by mice in the lit box as well as the number of transitions between the two boxes. Finally, we demonstrated that this drug was able to protect mice against pentylenetetrazole-induced convulsions. Our data show that BW A78U possesses some of the characteristic properties of the minor tranquilizers. However, since this compound binds to the benzodiazepine receptor with a very low affinity (IC50 = 13.6 microM), it can be assumed that this drug does not exert its behavioral effects through these receptors. It may interfere with other targets involving adenosine, another potent physiological regulator of neuronal excitability.