Prognostic factors were compared between 1,249 Caucasian and 360 Hispanic women with breast cancer. A significantly greater proportion of Hispanic women were less than 50 years of age at diagnosis compared to Caucasian women (P less than .0001). Significantly more Hispanic women presented with tumors larger than 3 cm in diameter and with positive axillary lymph nodes than did Caucasian women (P = .004 and P = .0001, respectively). Significantly more Hispanic women were estrogen receptor (ER) negative (P = .005). However, when examined by age groups, the relationships between ethnicity and extent of disease and ER status were observed only among women over 50 years of age. Multivariate analyses demonstrated that there was no difference in survival between Caucasian and Hispanic women once adjustments were made for the number of positive lymph nodes and ER status. Although complete data were not available, it appeared that the incidence of breast cancer is lower in this population of Hispanic women than in Caucasian women.