The aim of this study was to investigate the effect of amphetamine on rats classified in high and low drinkers in a schedule-induced polydipsia (SIP) task. First, male Wistar rats were submitted to a schedule-induced polydipsia (SIP) procedure for 20 days and divided in high and low drinkers if their average water intake was above or below the group median, respectively. Then subjects were submitted to surgery, and after 10 days of schedule-induced drinking recovery, amphetamine was administered in the medial prefrontal cortex. Results indicate a differential effect of amphetamine on high and low drinkers. Those results were discussed on the hypothesis of a different dopaminérgic function between high and low drinkers