Introduction. Theoretically, the physiological response to stress should inhibit the sexual response. This has been demonstrated experimentally in animal models, and correlationally in studies of human reproduction. It is reasonable to expect, then, that the stress response would be blunted during sexual arousal, and several researchers have found a pattern of decreasing cortisol during sexual arousal. Aim. In the present study, we explored individual differences in women's cortisol response to sexual arousal in a laboratory setting. We also examined how cortisol response in the laboratory related to a validated measure of sexual arousal functioning in real life. Main Outcome Measures. Cortisol levels were measured in saliva via enzyme immunoassay. Subjective arousal was measured by a self-report questionnaire, and genital arousal was measured by a vaginal photoplethysmograph. Methods. Subjective and physiological responses to an erotic film were assessed in 30 women. Saliva samples were taken at baseline and following the film. Results. The majority of women (N = 20) showed a decrease in cortisol; nine women showed an increase in response to an erotic film. The women who showed an increase in cortisol had lower scores on the Arousal, Desire, and Satisfaction domains of the Female Sexual Function Index. Genital arousal in the laboratory was not related to cortisol change. Conclusions. Women who show an increase in cortisol in response to sexual stimuli in the laboratory have lower levels of functioning in certain areas of their sexual life compared with women who show a decrease in cortisol. Stress related to sexual performance may interfere with sexual arousal.