Breast cancer is diagnosed at a younger age and a more advanced stage in African-American women than in White women. The authors investigated the effects of several factors, including race, on stage of breast cancer in women aged 20-54 years living in Atlanta, Georgia, and diagnosed between 1990 and 1992. A total of 251 African-American and 580 White women were interviewed and their medical records reviewed. By use of polytomous logistic regression, factors possibly influencing stage and racial differences in stage were studied. In African-American women, the odds of stage III/IV breast cancer at diagnosis were almost four times the odds in White women (odds ratio = 3.79, 95% confidence interval: 2.45, 5.89) and approximately two and one-half times for stage IIA or stage IIB disease (odds ratio = 2.57, 95% confidence interval: 1.66, 3.99; odds ratio = 1.94, 95% confidence interval: 1.31, 2.86, respectively). These racial differences appeared to be largely explained by insurance status, poverty, history of mammography, method of tumor detection, and obesity. Interventions targeting these factors could potentially lower the stage at diagnosis for African-American breast cancer patients and, in doing so, improve their survival and other outcomes.