Taioli et al. ( 1) reported that African-American women had significantly lower ratios of urinary estrogen metabolites (2-OHE1/16α-OHE1) than did Caucasian women. We would like to provide data to, in part, support these findings. We obtained urine samples with which to measure estrogen metabolites from 74 women with incident breast cancers and from 58 women receiving screening mammography who were found to be free of breast cancer. We found that African-American women had significantly lower 2-OHE1/creatinine levels than did Caucasian women ( Table 1 ), and this ethnic …