While large differences by race/ethnicity in breast cancer survival are well established, it is unknown whether differences in quality of chemotherapy delivered explain the racial/ethnic disparities in survival among black, Hispanic, Asian, and white women with breast cancer. We evaluated factors associated with time to initiation of adjuvant chemotherapy and chemotherapy completion and examined outcomes data among women with breast cancer. Patients who initiated chemotherapy later than 3 months after surgery were 1.8 times more likely to die of breast cancer (95 % CI 1.3–2.5) compared with those who initiated chemotherapy less than a month after surgery, even after controlling for known confounders or controlling for race/ethnicity. Women who completed chemotherapy had significantly higher survival compared with those who have not completed chemotherapy. Despite correcting for chemotherapy initiation and completion and known predictors of outcome, African American women still had worse disease-specific survival than their Caucasian counterparts. While a complete and timely adjuvant treatment among various ethnic populations would help to reduce racial disparities in survival, there are still other factors to be identified that may explain the remaining differences in survival between ethnic women with breast cancer.