The hippocampus is sensitive to high levels of glucocorticoids. During stress response, it suffers biochemical and cellular changes that affect functions such as spatial memory and exploratory behavior. In this study, we analyzed the influence of the neurosteroid progesterone (PROG), on stress-induced changes in urinary corticosterone (CORT) levels, spatial memory and exploratory behavior. Castrated adult male rats were implanted with PROG or vehicle (VEHI), and then exposed to chronic stress by overcrowding or ultrasonic noise for ten days. PROG and CORT levels were assessed in urine using high-performance liquid chromatography (HPLC). Implanted PROG inhibited stress-induced CORT raise, prevented spatial memory impairment in the Morris water maze, and eliminated increased exploratory behavior in the hole-board test. These results suggest protective effects of PROG against the corticosteroids raise and behavioral deficit generated by both stressful situations, possibly mediated by its anxiolytic mechanisms.