1. In the case of an intraperitoneal propranolol injection to rats (25 mg/kg), there was no modification in benzodiazepine and gamma-amino-butyric acid recognition sites since [3H]diazepam or [3H]-muscimol binding was not affected. 2. There was an increase in GABA stimulated-diazepam binding (100%, statistical risk lower than 1%). 3. This last result suggests that propranolol treatment can stimulate GABA-benzodiazepine receptor coupling.