Background: Acute Coronary Syndrome (ACS) poses a significant threat to cardiovascular health, involving sudden reduced blood flow to the heart, encompassing conditions such as unstable angina and myocardial infarction. Acute kidney injury (AKI) is a common complication in ACS patients, necessitating effective biomarkers for early detection. Methods: We conducted a prospective study involving 70 patients with acute coronary syndrome or heart failure to assess the efficacy of Neutrophil Gelatinase-Associated Lipocalin (NGAL) as a biomarker for AKI. Detailed clinical data, urine samples for NGAL immunoassay, and serum creatinine levels at baseline, 24 hours, and 48 hours were collected. Statistical analysis was performed, with a significance threshold set at P < 0.05. Results: The study population comprised 42 males and 28 females. Serum creatinine levels showed a significant increase over 48 hours. Mean urinary NGAL levels were significantly higher in the AKI group (486.2) compared to the non-AKI group (72.5), indicating a robust correlation (r = 0.82, P < 0.05) between NGAL and AKI. Discussion: Unstable angina and myocardial infarction were characterized in the context of ACS. Our findings support the potential of NGAL as a superior biomarker for early AKI detection compared to serum creatinine, aligning with previous research on NGAL's effectiveness, particularly in high-risk scenarios. Conclusion: This study underscores the significant correlation between urinary NGAL levels and AKI in ACS patients, suggesting NGAL's potential as a valuable early biomarker. However, limitations include a relatively small sample size and six-month study duration, warranting further research with larger cohorts and extended follow-up.