Uncertainty exists regarding the magnitude of excess mortality from localized breast cancer at long follow-up times (greater than 15 years) since diagnosis and regarding the effects of race and age as prognostic factors at all follow-up times. Long-term survival was determined in 1141 patients (311 white, 830 black) diagnosed as having localized breast cancer with and without positive axillary lymph nodes, but without any signs of complete or incomplete skin, muscle, or chest wall attachment. Survival curves were estimated by means of actuarial methods; prognostic factors were evaluated with the Cox's regression analysis. Survival from all causes was 62%, 43%, 33%, 25%, and 18% at 5, 10, 15, 20, and 30 years, respectively. Breast cancer-specific survival was 76%, 65%, 63%, 61%, and 59% at 5, 10, 15, 20, and 30 years, respectively. Breast cancer-specific hazard rates exceeded those expected in the general population by 119 times, 53 times, 12 times, and 6 times at 0 to 5, 5 to 10, 10 to 20, and 20 to 25 years, respectively. Of the 395 patients enrolled after 1968 who had modified radical or radical surgery, 338 had known number of positive nodes and size of tumor. Breast cancer-specific survival was significantly increased with: a decreasing number of positive lymph nodes, 0, 1 to 3, and 4 or more (P = 0.000); later year of diagnosis (1974 or before versus 1975 or later) (P = 0.000); and possibly, tumor size of 7.0 cm or less (P = 0.09). When these variables were controlled, no significant association of age at diagnosis or race with breast cancer-specific survival was found. These data suggest that the number of nodes, year of diagnosis and, possibly, tumor size are important prognostic factors for survival, but race and age are not. Also, excess mortality may exist at late intervals; however, it is small in relation to other causes.