Post-trial administration of secoverine (0.5, 1 and 2.5 mg/kg), a presynaptic muscarinic blocker, improved retention in mice tested in a passive avoidance task. The nootropic drug oxiracetam (50 mg/kg), given before both acquisition and retention trial, had no effect alone, but significantly enhanced secoverine improving effects. Performance improvements were also found in combining ineffective doses of the two compounds. Even if not necessarily through a direct and specific action, oxiracetam might activate cholinergic function. Thus, performance improvements resulting from the combination of oxiracetam and secoverine may be due to a simultaneous activation of different cholinergic mechanisms.