Consistent with animal models and experimental studies with humans facing other 'background' stressors, women at familial risk for breast cancer have been reported to have stronger cortisol responses to laboratory stressors. To explore the relevance of these findings to daily life, we compared work-stress cortisol responses in women with >or=1 first-degree relative with breast cancer (FH+, n = 74) to women without this risk factor (FH-, n = 141). Repeated-measures ANOVA revealed a group by time interaction (p <or= 0.05) with FH+ women having higher (p <or= 0.05) urinary cortisol levels than FH- during work, but not at home or during sleep. They also had a higher percentage increase between nadir cortisol levels and work levels. These results provide evidence that the heightened cortisol responses of FH+ women also apply to daily life stressors, and suggest the need for additional research to explore the possibility that accentuated hypothalamic-pituitary-axis responses to such stressors may increase health risk for these women.