Objectives. To explore the role of nutrient patterns in the etiology of breast cancer (BC) among Uruguayanwomen. Methods. A principal component analysis was conducted. The study included 442 newly diagnosedcases of BC and 442 hospitalized controls. Results. Two dietary patterns derived from factor analysis and werelabeled as high-meat and antioxidants patterns. Whereas the high-meat pattern was directly associated withBC risk (OR for the highest versus the lowest quartile = 3.50, 95 % CI 1.94-6.30, p-value for trend <0.0001),the antioxidants pattern displayed a protective effect (OR=0.44, 95 % CI 0.27-0.74). Its negative associationwas stronger for postmenopausal than for premenopausal women (OR=0.63, 95% CI 0.51-0.79 vs. OR=0.89,95% CI 0.50-1.56, respectively). Both strata were heterogeneous (p=0.004). The high-meat pattern was moreassociated with BC risk among patients with family history of BC compared with participants without it, butresults did not differ by histology. In contrast, the antioxidants pattern was more associated with non-ductalcancers (OR=0.50 [95 % CI 0.35-0.69]) than with ductal cancers (OR=0.72, 95 % CI 0.58-0.88, heterogeneityp-value=0.03). Conclusions. Results support an association between the high-meat and antioxidant dietarypatterns and BC risk. Furthermore, findings suggest that gene-environmental interactions may be importantin BC etiology.