The nootropic drug, oxiracetam (25 or 50 mg/kg i.p.), was tested in two inbred strains of mice, subjected to shuttle-box avoidance training. The drug improved avoidance acquisition in good performers BALB/c mice more than in poor performers C57BL/6 mice. In both cases the avoidance facilitating action was evident only if training was preceded by a five-day pretreatment. The nootropic prototype, piracetam (100 mg/kg), facilitated avoidance acquisition in pretreated BALB/c, but not in C57BL/6 mice.