Pulmonary manifestations of cardiac diseases are reviewed and the contribution of pulmonary function assessment in diagnosis, management and prognosis of these diseases is being emphasized. Inborn and acquired diseases of the heart exert pathological effects on pulmonary hemodynamics and later on also on lung structure, clinically manifested by pulmonary symptomatology and abnormalities in pulmonary function. The basic mechanisms of pulmonary function derangement include pulmonary congestion and hyperreactivity of the airways as a consequence of increased blood pressure or flow in the pulmovascular network (postcapillary or hyperkinetic pulmonary hypertension). The severity of the given cardiac disease determines also the condition of pulmonary function. Thus examinations of pulmonary function substantially contribute to the classification of the functional state and to optimal choices in therapeutic strategy. Appropriate surgical or medical therapeutic procedures can improve the hemodynamic conditions in the pulmonary vascular network. This, in turn, leads to partial regression of morphological changes in the pulmonary parenchyma and thus to gradual improvement of pulmonary function. (Tab. 4, Fig. 4, Ref. 62.)