In patients with pulmonary disease, it is often challenging to distinguish exacerbated pulmonary disease from congestive heart failure (CHF). The impact of B-type natriuretic peptide (BNP) measurements on the management of patients with pulmonary disease and acute dyspnea remains to be defined. This study evaluated the subgroup of 226 patients with a history of pulmonary disease included in the BASEL Study. Patients were randomly assigned to a diagnostic strategy with (n = 119, BNP group) or without (n = 107, clinical group) the use of BNP levels provided by a rapid bedside assay. Time to discharge and total cost of treatment were recorded as the primary end points. Baseline characteristics were similar in patients assigned to the BNP and control groups. Comorbidity was extensive, including coronary artery disease and hypertension in half of patients. The primary discharge diagnosis was CHF and exacerbated obstructive pulmonary disease in 39% and 33%, respectively. The use of BNP levels significantly reduced the need for hospital admission (81% vs 91%, P = .034). Median time to discharge was 9.0 days in the BNP group as compared with 12.0 days (P = .001) in the clinical group. Median total cost of treatment was $4841 in the BNP group as compared with $5671 in the clinical group (P = .008). Inhospital mortality was 8% in both groups. CHF is a major cause of acute dyspnea in patients with a history of pulmonary disease. Used in conjunction with other clinical information, rapid measurement of BNP reduced time to discharge and total treatment cost of these patients.