e11004 Background: To examine the relationship between age and lymph node ratio (LNR, number of positive nodes divided by number of examined nodes), and to determine their effects on breast cancer mortality. Methods: A total of 38,146 cases of women aged 50+ years, diagnosed in 1988-1997 (cohort 1) and 1998-2006 (cohort 2) with a unilateral histologically confirmed T1-T2 node positive surgically treated primary breast carcinoma, without distant metastases, were selected from the Surveillance, Epidemiology, and End Results (SEER). Correlations were computed by linear regression. Survival primary end-point was breast cancer specific survival (BCSS). Effects of age (elderly 70+, vs. 50-69 years) and LNR (high > 0.25, vs. < = 0.25) were adjusted in Cox models for registry area, marital status, race, histological grade, hormone receptor status, tumor size, numbers of nodes, and local therapies. Results: In both cohorts, LNR correlated with age, increasing from 0.26 in patients 50 years old, to 0.29 in patients 70+ years (p < 0.0001). In multivariate analysis, high age and high LNR were associated with increased risks of breast cancer mortality, with hazard ratio for age 1.10 (95%CI 1.04–1.17) and LNR 1.53 (1.40–1.68) (cohort 1), 1.61 (1.46–1.78) and 1.65 (1.43–1.90) (cohort 2). BCSS at 10-years in elderly women with high LNR was 52.3%, as compared to 57.5% in younger women (p = 0.0003) (cohort 1). Conclusions: Older age at diagnosis correlated with higher LNR. Elderly women with a higher tumor burden indicated by higher LNR had a significant increased risk of breast cancer death as compared with younger post-menopausal women. No significant financial relationships to disclose.