BACKGROUND: Cardiovascular disease is a significant contributor to the disease burden in geriatric patients. Underlying systemic inflammation is thought to be the cause of age-related changes in the bone marrow and a major risk factor for atherosclerosis. The purpose of the study was to assess the accuracy of these hematological biomarkers in predicting 30-day mortality in older patients with acute coronary syndrome (ACS). METHODS: This was a prospective observational study of 601 older adult patients (age > 60 years) with ACS who underwent percutaneous coronary intervention over two years (2017-2019). The relationship between baseline hematological parameters and mortality was assessed during the 30-day follow-up. Logistic regression analysis and receiver operating characteristic curve analysis were done to evaluate for diagnostic accuracy of various hematological parameters. RESULTS: The mean age of presentation was 77 ± 17 years. The mean neutrophil-lymphocyte ratio (NLR) value was 5.07 ± 4.90 and the mean platelet-lymphocyte ratio (PLR) value was 108.65 ± 85.82. On univariate analysis, total leucocyte count [odds ratio (OR) = 0.85, P = 0.021], hematocrit (OR = 0.91, P = 0.018), NLR (OR = 1.10, P = 0.001) and PLR (OR = 1.05, P = 0.001) were associated with mortality. On receiver operating characteristic curve analysis, NLR predicted mortality with 68.1% and PLR with 65.7% accuracy. On multivariate analysis, NLR (OR = 1.096, 95% CI: 1.006-1.15, P = 0.035) was an independent predictor of 30-day mortality. CONCLUSIONS For the risk classification of all elderly ACS patients, we highly advise using NLR rather than the total white blood cell count.