Hypertension may affect the diagnostic performance of B-type natriuretic peptide (BNP). The objective of the present study was to assess the impact of a history of hypertension or blood pressure elevation on admission on the diagnostic performance of BNP in the diagnosis of heart failure (HF) in patients with acute dyspnea. BNP levels were measured using a rapid point-of-care device in 1,586 patients with acute dyspnea. In patients with HF, BNP levels did not differ between those with and without histories of hypertension. Conversely, in patients without HF, a history of hypertension was associated with higher median BNP levels (38 pg/ml [interquartile range 13 to 119] vs 21 pg/ml [interquartile range 7 to 64], p <0.001). The areas under the receiver-operating characteristic curves were 0.88 and 0.93 for those with and without histories of hypertension, respectively (p <0.001). Blood pressure elevation on admission did not affect the diagnostic accuracy of BNP (areas under the curve 0.90 in the 2 groups). In conclusion, although a history of hypertension is associated with higher BNP levels in patients with acute dyspnea without HF, the impact on the overall diagnostic performance of BNP is modest. Accordingly, BNP performs well as an indicator of HF in patients presenting in emergency departments regardless of a history of hypertension or elevated blood pressure on admission.