Background: In patients with stable coronary artery disease (SCAD), the neutrophil–lymphocyte ratio (NLR) is thought to be an independent predictor of death and myocardial infarction (MI). In patients suffering from acute coronary syndrome (ACS), NLR also has prognostic significance. Nevertheless, further research has to be done on the diagnostic efficacy of NLR in ACS patients. Objective: To ascertain if NLR can accurately predict troponin elevation in patients who arrive at the Emergency Department with NST-ACS. Patients and Methods: This is a prospective observational study that was carried out on 100 patients who presented to the Emergency Department at Ain Shams University Specialized Hospital between June 2018 and March 2019 with angina or angina-equivalent during the first 12 hours of symptom onset. Results: Two groups were created from the study population: a troponin-positive group (n = 50) and a troponin-negative group (n = 50). The patients' average age was 55.8 ± 11.3, with 77% of them being males. There was no discernible difference in the two groups' levels of platelets, WBCs, or hemoglobin. The group that had positive troponin levels had a considerably higher neutrophil count (p < 0.001). The group that tested positive for troponin had a considerably greater NLR (2 vs. 3.9, P < 0.001). In terms of predicting follow-up troponin positive, a cutoff value of 3.4 for NLR assessed at admission exhibited 84% sensitivity and 84% specificity. The amount of troponin alteration and NLR were shown to be extremely significantly correlated (p value <0.01). Conclusion: NLR is a diagnostic technique that can be used to distinguish between people who have ACS. NLR is an accessible, affordable, and straightforward metric that may be utilized for NSTEMI diagnosis.