Abstract Background and Aims Previous studies have shown that increased blood urea nitrogen to creatinine ratio (BCR) is a poor prognostic marker in patients with some chronic diseases or in the general population. However, the clinical implication of BCR in elderly dialysis patients is unknown. The purpose of this study was to verify the association of BCR with the risk of death in elderly patients starting hemodialysis. Method The Korean Society of Geriatric Nephrology Retrospective Cohort consists of patients who started maintenance hemodialysis from January 1, 2010 to December 31, 2017 at 17 nephrology centers in Korea. After excluding patients with malignancy or estimated glomerular filtration rate 30 ml/min/1.73 m2 or greater, we retrospectively analyzed 2,183 patients. The main predictor was patients BCR at the time of hemodialysis initiation and subjects were divided into four groups according to their BCR quartile. The main outcome was all-cause mortality. Results During 7,545 person-years of follow-up, 1,382(63.3%) patients died. Patients in the high BCR group died more (60.9%, 59.3%, 62.5% and 70.5% for the 1st to 4th BCR quartiles, respectively, P=0.001). In multivariate Cox proportional hazard model, BCR increase by one was associated with increased risk of death (HR 1.01; 95% CI, 1.01-1.02). This model was adjusted for age, sex, body mass index, cause of renal disease, hypertension, diabetes, ischemic heart disease, cerebrovascular disease, congestive heart failure, eGFR, hemoglobin, albumin, calcium and phosphorus. Compared to 3rd quartile of BCR group, 4th quartile group was associated with increased risk of death (HR, 1.30; 95% CI, 1.12-1.51). Conclusion High BCR is a predictor of high mortality in elderly patients starting hemodialysis. This result suggests that more attention should be paid to elderly patients starting hemodialysis with high BCR.