Background: The role of brain natriuretic peptide (BNP) is well known as a screening test to detect heart failure in patients complaining dyspnea at emergency department. In some studies, the elevation of BNP was associated with acute ischemic stroke. But in acute ischemic stroke, the role of BNP is less established to detect comorbid cardiac events such as heart failure or ischemic heart disease. Methods: We included consecutively 372 patients with acute ischemic stroke who underwent a comprehensive clinical examination and measurements of BNP, cardiac enzyme, and other biomarkers. Echocardiography was performed after stabilization to evaluate cardiac embolism. We evaluated the usefulness of BNP as compared with other biomarkers such as high-sensitivity C-reactive protein (hsCRP), troponin, homocystein, lipoprotein (a) to detect comorbid heart failure or ischemic heart disease. Results: Of the 372 patients with acute ischemic stroke (mean age 65 짹 13; female 44%), heart failure and ischemic heart disease were diagnosed in 16 (4.3%) and 20 patients (5.4%), respectively during admission. BNP plasma levels in the patients with heart failure (367 짹 295 pg/ml, p < 0.001) or ischemic heart diseases (358 짹 329 pg/ml, p < 0.001) were higher than in the patients without cardiac events (72 짹 116 pg/ml). There was no significant difference in hsCRP, troponin, homocystein and lipoprotein (a) between patients with or without cardiac events. BNP remained a marker of cardiac events after adjustment for other variables, including age, sex, and atrial fibrillation. A BNP cut-point of 100 pg/ml was 84% sensitive and 81 % specific for diagnosing cardiac events. Negative predictive value of BNP cut-point of 100 pg/ml was 98%. Conclusions: In patients admitted with acute ischemic stroke, BNP may be useful to screen or identify comorbid cardiac events such as heart failure and ischemic heart disease.