We used data from a study of racial differences in cancer patient survival to examine the association between estrogen receptor status and the intake of nutrients and food groups among 689 black and white women, ages 20-79, with breast cancer newly diagnosed in 1985 and 1986. We reviewed medical records and collected interview data, including a 34-item food frequency questionnaire. Consistent with published reports, we found positive estrogen receptor status to be positively associated with age and inversely associated with parity and oral contraceptive use. Whites were more likely than blacks to have estrogen receptor-positive tumors. We examined eight nutrients and six food groups in multivariate analyses for association with estrogen receptor status. After adjusting for age, race, usual body mass index, and parity, a high percentage of calories from fat was associated with estrogen receptor-positive cancer, and a high percentage of calories from carbohydrates was associated with estrogen receptor-negative breast cancer. These findings indicate that women with breast cancer who are on diets with a high percentage of calories from fat may be more likely to develop estrogen receptor-positive cancers.