A pretreatment with dibenamine (10 mg/kg) impaired the facilitatory learning action of both amphetamine (2 mg/kg) and nicotine (0.2 mg/kg), in a shuttle-box. However, this effect was not noticed in medullectomized rats. Pretreatment with hydralazine (5 mg/kg) or papaverine (10 mg/kg) had no effect on the action of 2 mg/kg amphetamine, but significantly depressed the effect of 0.5 mg/kg amphetamine and that of nicotine (0.2 mg/kg). The participation of peripheral mechanisms on the facilitatory learning action of amphetamine and nicotine is discussed.