THE potential of DuP 753, an angiotensin II receptor antagonist, to improve cognitive performance was assessed in a mouse habituation paradigm. On repeated daily testing DuP 753 (10.0 ng kg-1 p.o.) enhanced the basal cognitive performance of mice (decrease in latency to move from the light to the dark compartment and increases in the rears, line crossings and percentage of time spent in the dark compartment) and overcame the cognitive impairment induced by the administration of scopolamine (0.25 mg kg-1 i.p.). These findings further implicate the modulation of mental function by angiotensin II.