The stress response is regulated by two primary neuroendocrine systems, the hypothalamus-pituitary-adrenocortical (HPA) and sympathetic adrenomedullary (SAM) systems. This study investigated gender differences in the activities of these two systems in response to acute psychological stress. Subjects were categorized according to their score in Spielberger's Trait Anxiety Inventory (STAI), which assesses the predisposition to personal anxiety. High (STAI score >or=55)- and low (STAI score <or=45)-anxiety groups were selected. A video of corneal surgery was served as the stressor for 15 min. Salivary cortisol and amylase levels were used as indices of the HPA and SAM activities, respectively. beta-endorphin was also assayed as a possible index of HPA activity. There were no differences in the resting salivary parameters among the groups. As expected, cortisol and amylase levels were significantly increased in all groups after the stressful video viewing. There were no gender differences in amylase levels in either the high- or low-anxiety groups. However, cortisol levels in highly anxious females were significantly lower than those in highly anxious males. Our findings show that highly anxious females exhibited lower cortisol release than highly anxious males, suggesting that high trait anxiety in females may be associated with an inability to respond with sufficient activation of HPA under acute psychological stress.