Cough and wheezing are common findings in left heart failure. However, it is still questionable whether nonallergic bronchial hyperresponsiveness, the hallmark of asthma, is also associated with this condition. In 12 subjects with acute decompensation of chronic postischemic LV failure, we assessed the PC20 methacholine during an episode of acute LV failure and after five to 15 days of intensive diuretic therapy. Weight, arterial blood gases, plethysmographic lung volumes, and expiratory flows were also measured on both visits. Extravascular lung water was estimated indirectly with a radiologic score. During acute decompensation, six subjects had significant airway obstruction and eight had a PC20 less than or equal to 16 mg/ml (significant bronchial hyperresponsiveness). After diuretic therapy, subjects improved significantly, losing an average of 2.2 kg, but they still had chronic LV failure and evidence of an obstructive breathing defect. Although mean PC20 was unchanged, three subjects had significantly improved PC20 after treatment. We conclude that: (1) left ventricular failure is often associated with mild bronchial hyperresponsiveness, although it is not excluded that smoking and the resulting possibility of bronchial obstruction can also play some role; and (2) acute treatment does not generally alter bronchial responsiveness to methacholine, suggesting that chronic LV failure can cause chronic changes to the airways.