OBJECTIVE: To assess the relation between work-related stressors and breast cancer incidence and prognostic characteristics (estrogen receptor status, grade, lymph node status, size, stage) at the time of diagnosis. METHODS: The 18,932 women included in the Danish Nurse Cohort reported work-related stressors in 1993 and again in 1999 and were followed until the end of 2003 in national registries. Prognostic characteristics were obtained from a clinical database and fewer than 0.1% were lost to follow up. RESULTS: During follow-up, 455 women were diagnosed with breast cancer. Neither women with high work pressure (HR = 1.17; 95% CI: 0.79, 1.73) nor women with self-reported low influence on work organization (0.98; 0.69, 1.39) or long working hours (0.93; 0.54, 1.58) were at higher risk of breast cancer than women with no such stressors. Women with high work tempo had a slightly higher risk of breast cancer (1.25; 1.02, 1.54) than women with a suitable work tempo, but there was no dose-response effect. There were no clear differences in the prognostic characteristics of breast tumors diagnosed in women with and without work-related stressors. CONCLUSIONS: Work-related stressors do not affect breast cancer risk or the prognostic characteristics of incident breast cancers at the time of diagnosis. These results may be a comfort to working women and can hopefully prevent self-blaming among women who develop breast cancer.