The effects of three quinoline derivatives, PK 8165 07.5 mg/kg). PK 9084 (7.5 mg/kg) and CGS 8216 (1 and 10 mg/kg), alone and in combination with chlordiazepoxide (5 mg/kg), were investigated in the social interaction test of anxiety. PK 8165 had no effect on social interaction but both PK 8165 and PK 9084 in combination with chlordiazepoxide produced sedation. PK 9084 exhibited a partial anxiolytic profile reflected by a drug x light interaction in the familiar test conditions. CGS 8216 (1 mg/kg) showed no significant effects on social interaction, but did counteract the sedative effect of chlordiazepoxide. The 10 mg/kg dose of CGS 8216 reduced social interaction between pairs of animals in familiar test conditions which is indicative of an anxiogenic effect. These intrinsic anxiogenic properties of CGS 8216 demonstrate that it cannot be considered an inert benzodiazepine antagonist.