Women and men differ in their physiological and psychological stress response but only a few studies have analyzed this sex difference in a naturalistic setting and focused on cognitive stress appraisal. In the present study, the salivary cortisol concentration of 24 female and 22 male subjects was measured before and several times after an oral academic presentation given by themselves (stress condition) or given by a fellow student (control condition). Feelings of subjective stress and nervousness were assessed simultaneously to the saliva samples and a questionnaire for cognitive stress appraisal was conducted right before the oral presentation. In the stress condition, the presentation led to a significantly higher cortisol increase than in the control condition. Sex differences were shown concerning the subjective stress feelings, which were higher in women, whereas there were no sex differences in cortisol release. Women showed a disadvantageous cognitive appraisal compared to men in both conditions. There was an interaction effect of sex and condition: women reported to feel equally challenged in both conditions whereas men felt significantly more challenged by their own presentation than by the presentations of their fellow students. The result that men's cognitive appraisal was more influenced by an academic stressor than women's and that women felt subjectively more stressed whereas there was no difference concerning the cortisol response is discussed in consideration of evolutional and biological aspects.