The heart and the lungs are strictly integrated both mechanically and functionally in what is now called the cardiopulmonary unit [1-4]. As a consequence, an abnormality of either component of this cardiopulmonary unit quickly alters the physiology of the other. In fact, right ventricular dysfunction and failure secondary to lung disease (i.e. cor pulmonale) are well known; on the other hand the impairment of lung function induced by left heart failure seems obvious, but the knowledge of its pathophysiological mechanism is still incomplete. In this article we will review the structural and functional changes induced by congestive heart failure on the lungs, their relation to the hemodynamic abnormalities and response to therapeutic interventions.