The effects of Dehydroepiandrosterone (DHEA) and its sulfate ester, Dehydroepiandrosterone sulfate (DHEAS) on performance in various cognitive and affective tasks were investigated. Ovariectomized rats (n = 48) received 0.0, 3.0, or 7.5 mg/kg s.c. of DHEA or DHEAS suspended in 10% ethanol/sesame oil v/v. For the cognitive tasks (water maze, Y-maze, passive avoidance, and object recognition), subjects were injected after training trials. For the affective tasks (tail flick, open field, and elevated plus-maze), subjects were injected 1 or 24 h prior to testing. DHEA deceased latencies and trials to criterion in the water maze, and decreased motor activity in the open field at 24 h postinjection. DHEAS decreased latencies to the goal arm in the Y-maze and reduced motoricity and the number of entries into the center of a brightly lit open field, both 1 and 24 h after injection. These findings suggest that DHEA and DHEAS may alter performance on cognitive tasks due to motor or anxiety effects. (C) 1999 Elsevier Science Inc.