Cognition-enhancing effects of no-otropic drugs are currently ascribed to an increase in arousal level. In order to test this hypothesis, we studied the effects of three doses of oxiracetam (25, 50 and 100 mg/kg IP) on a radial maze task and on slow wave sleep (SWS) latency in a familiar environment. The 25- and 100-mg/kg doses, but not the 50-mg/kg, significantly improved performance in the memory task. On the other hand, SWS latency was significantly increased by 50 and 100 mg/kg, with the effect of the 25-mg/kg dose going in the same direction but only approaching significance. These results give only a partial support to the "arousal factor hypothesis." Other factors are probably involved in the promnesic effects of oxiracetam.