We report the case of an 82-year old male patient without history of chronic obstructive lung disease in whom a sudden respiratory distress syndrome with sibilant rales in both lungs revealed a moderately severe pulmonary embolism, later confirmed by angiography. Bronchospasm occurring in the acute phase of pulmonary embolism may be expressed as acute asthma refractory to bronchodilators. This bronchoconstriction, seldom detectable clinically, seems to be related to regional alveolar hypocapnia in the territories embolized and to platelet-produced mediators, through a vagus nerve-mediated reflex. It must not hide pulmonary embolism, particularly in a suggestive context and when bronchodilators are ineffective.