Background: Acute carbon monoxide (CO) poisoning is a common toxicity emergency that leads in many occasions to morbidity and mortality. Acute myocardial injury is commonly observed among acute carbon monoxide poisoned patients and cardiac toxicity is found to be the cause of mortality in the majority of cases. Some studies recorded normal values of cardiac troponins in cases of acute CO poisoning with cardiac affection. Hence it is important to search for novel and sensitive biomarkers to diagnose cardiac ischemia in these cases. Brain natriuretic peptide (BNP) is a cardiac hormone which is produced mainly in the ventricular myocardium in response to myocardial hypoxia. Aim: The present study aims to investigate the value of BNP measurement in detection of cardiac toxicity in acute carbon monoxide poisoning. Methods: The present study was conducted on 42 patients with acute CO poisoning admitted to the Poison Control Centre of Ain Shams University hospitals (PCC-ASUH). Routine laboratory tests and ECG were done on admission in addition to determination of the level of BNP and determination of troponin I. Results: Analysis of the results showed that there is an increase in the levels of BNP in patients suffering from acute CO poisoning with high levels seen in those with ischemic changes recorded by ECG. Conclusions: The present study concluded that plasma BNP levels could be used as a specific reliable biomarker of cardiac toxicity in patients with acute CO poisoning.