The association between body fat distribution and breast cancer risk was studied in 5923 pre- and 3568 post-menopausal women, participating in a breast cancer screening project (the DOM-project in Utrecht, the Netherlands). Cases were fifty six premenopausal women and thirty eight postmenopausal women with breast cancer detected at screening or afterwards. Controls were women participating in the breast cancer screening project without breast cancer. Waist- and hip circumferences, height and weight were measured at screening, before diagnosis of breast cancer. In postmenopausal women the estimated relative risk of women in the upper tertile of waist/hip ratio compared with women in the lower tertile was 1.89 (95% CI 0.80-4.48), (test for trend p = 0.11). The estimated relative risk of women in the upper tertile of waist circumference compared with women in the lower tertile was 2.86 (95% CI 1.12-7.32), (test for trend p = 0.08). The association between waist circumference and breast cancer was stronger than the association between any of the other anthropometric variables and breast cancer. In premenopausal women the association between fat distribution and breast cancer was equivocal.