Objective · To study the correlation between brain natriuretic peptide (BNP) in plasma and functional outcome in patients with acute ischemic stroke after intravenous thrombolysis and its clinical significance. Methods · An analysis was performed on 141 cases of acute ischemic stroke patients with intravenous thrombolysis. According to the modified Rankin Scale (mRS) 3 months after thrombolysis, the patients were divided into the good outcome group (mRS ≤ 1) and the poor outcome group (mRS>1). BNP level indicators after thrombolysis were compared between the two groups. The receiver operator characteristic (ROC) curve was used to analyze the ability of BNP level to predict the functional outcome 3 months after thrombolysis, and the influence of some other relevant factors was adjustedLogistic regression analysis. Results · Compared with the good outcome group, the level of BNP in the poor outcome group was significantly increased (P0.003). According to ROC curve analysis, the elevated BNP level (BNP>202.6 pg/mL) had a certain predictive ability for poor functional outcome 3 months after intravenous thrombolysis in patients with acute ischemic stroke. Elevated BNP level was an independent predictor of functional outcome 3 months after intravenous thrombolysis in patients with acute ischemic stroke (OR2.406, 95% CI 1.0695.417, P0.034). Conclusion · Elevated plasma BNP level after thrombolysis is significantly associated with poor functional outcome in patients with acute ischemic stroke after intravenous thrombolysis, suggesting a predictive role of BNP for poor outcome 3 months after intravenous thrombolysis.