Atherosclerosis is the pathognomic sign of ischaemic heart disease. Inflammation of the coronary artery contributes to the development of atherosclerosis. Neutrophil-to-lymphocyte ratio (NLR) has been reported to predict the risk of CAD and associated events in patients with ST-Segment elevation myocardial infarction (STEMI). This study was done to investigate the role of neutrophil-to-lymphocyte ratio (NLR) in predicting in-hospital adverse cardiac events in patients with STEMI thrombolysed with streptokinase (STK). This cross sectional descriptive type of study was conducted in the Department of Cardiology, Mymensingh Medical College Hospital, Mymensingh, Bangladesh from August, 2017 to October, 2018. The STEMI patients, thrombolysed with STK had blood samples at admission, analyzed for complete blood counts and NLR calculated. They were grouped into two, low and high NLR, taking 4.50 as cut-off value. Chi square test was used to compare rate of adverse events and death in hospital stay. Logistic regression analysis was used to estimate predictive ability of NLR for in-hospital cardiac events. A total of 87 (39.90%) patients had complications. Patients in high NLR group had higher rate of complications (48.3% vs. 22.5%, p<0.001) in hospital than those in low NLR group. Arrhythmias (21.1% vs. 9.9%, p<0.041), heart failure (27.9% vs. 14.1%, p=0.024), cardiogenic shock (16.3% vs. 4.2%, p<0.011), death (6.8% vs. 2.8%, p=0.227), re-infarction /post MI angina (4.1% vs. 0.0% p=0.084) occurred more in high NLR group. Mean NLR was significantly different between Group I and Group II (3.11±0.84 vs. 10.20±6.08, p<0.0001). Multivariate regression analysis showed NLR an independent predictor of in-hospital adverse cardiac events (p<0.0001). High on admission NLR is an independent predictor for in-hospital adverse cardiac events in patients with STEMI thrombolysed with streptokinase.