Aim: This study investigated the prognosis in patients with acute coronary syndrome (ACS) and the relationship with systemic inflammatory indices such as neutrophil-lymphocyte ratio (NLR), platelet -lymphocyte ratio (PLR), systemic immune inflammation index (SII), systemic inflammatory response index (SIRI), prognostic nutritional index (PNI). Material and Methods: A total of 215 patients diagnosed with ACS between 01.09.2023 and 01.03.2024 were evaluated retrospectively. Patients were divided into two groups as survivors and non -survivors. NLR, PLR, SII, SIRI and PNI levels were statistically compared between these two groups. Variables that may be associated with mortality were subjected to receiver operating characteristic (ROC) analysis. Results: NLR, PLR, SII and SIRI were significantly higher, whereas PNI was lower in the non -surviving group (p<0.05 for all). According to ROC analysis, SII had the highest and PLR the lowest predictive power of the inflammation indices (Area Under Curve [AUC] : 0.919 and 0.827, respectively). Discussion: NLR, PLR, SII, SIRI and PNI levels may predict risk stratification and prognosis in patients with ACS.