ObjectivesWe examined the association between comorbidity and long-term mortality from breast cancer and other causes among African-American and white women with breast cancer. MethodsA total of 170 African-American and 829 white women aged 40-84. years were followed for up to 28. years with median follow-up of 11.3 years in the Health and Functioning in Women (HFW) study. The impact of the Charlson Comorbidity Score (CCS) in the first few months following breast cancer diagnosis on the risk of mortality from breast cancer and other causes was examined using extended Cox models. ResultsMedian follow-up was significantly shorter for African-American women than their white counterparts (median 8.5 years vs. 12.3 years). Compared to white women, African-American women had significantly fewer years of education, greater body mass index, were more likely to have functional limitations and later stage at breast cancer diagnosis, and fewer had adequate financial resources (all P < 0.05). Proportionately more African-American women died of breast cancer than white women (37.1% vs. 31.4%, P = 0.15). A positive and statistically significant time-varying effect of the Charlson Comorbidity Score (CCS) on other-cause mortality persisted throughout the first 5. years of follow-up (P < 0.001) but not for its remainder. Conclusions Higher CCS was associated with increased risk of other-cause mortality, but not breast cancer specific mortality; the association did not differ among African-American and white women. © 2014 Elsevier Inc.