OBJECTIVE@#The purpose of this study was to test the hypothesis that an increase in the neutrophil-to-lymphocyte ratio (NLR) increases the risk of in-hospital density in patients aged 65 and older, who are hospitalized in intensive care through the emergency rooms.@*METHODS@#A retrospective medical record study was conducted on elderly patients who were admitted to intensive care units via the emergency room. The exclusion criteria were data loss, intensive care unit reentry, cerebrovascular accidents, hematologic disease, and trauma cases.@*RESULTS@#The study included 526 patients; the mean age was 79, and 261 (49.6%) were male. The in-hospital mortality was 18.4% (97 patients). The initial NLR was higher in the non-survivor group than the survivor group, but the difference was not statistically significant (9.82±11.02 vs. 11.48±6.11, P=0.080). In multivariate logistic analysis, the initial NLR had no statistical significance, and the odd ratio was increased from one day later. Comparing the receiver operating characteristic curve of the NLR and Acute Physiology and Chronic Health Evaluation II (APACHE II) and Simplified Acute Physiology Score II (SAPS II) scores, the NLR showed an increase in the area of under curve (AUC) value over time as well as the highest AUC with the SAPS II scores.@*CONCLUSION@#In elderly adults, early NLR was found to have weak power to predict in-hospital mortality. Over time, the NLR values more than two days after intensive care unit admission may be useful in predicting the in-hospital mortality for older patients. This may be due to the delay in the immune response and the complex medical history.