As part of a case-control study of breast cancer in Hawaii, self-reported data on height, weight at various ages, breast size, shoe size, and triceps skinfold thickness were collected from 138 Japanese postmenopausal cases, 134 Caucasian postmenopausal cases, 154 Japanese neighborhood controls, and 142 Caucasian neighborhood controls. In a multiple covariance analysis, cases of both ethnic groups were slightly heavier (at all ages) and more obese (based on a weight-corrected-for-height index) than were controls, although none of the differences was statistically significant. Among the Japanese only, cases were also taller, had a greater body surface area (computed from the height and weight data), and had a larger shoe size than did the controls. The latter finding was statistically significant (p less than 0.05). Odds ratios were computed by multiple logistic regression analysis and revealed no additional relationships; however, there were suggested dose-response gradients for height, weight at age 20, and body surface area in the Japanese women and for breast size in the Caucasian women. A further analysis of risks based on changes in relative body weight between young adult life (age 20) and current age was also negative. Overall, these findings offer only weak support for an association between weight or obesity and breast cancer risk and suggest that anthropometric indices are at best very indirect indicators of true etiologic factors for breast cancer.