Pulmonary involvement in patients with heart disease is common. The understanding of cardiopulmonary interaction is pivotal for the diagnosis and management of cardiac conditions and for establishing a correct individualized treatment. For this reason, pulmonary function tests (PFTs), along with examining gas exchange and radiological evaluation, are a fundamental part of the multidisciplinary approach for cardiac patients. Spirometry is the most common PFT, and it measures volume mobilization with inspiratory and expiratory maneuvers. The administration of a bronchodilator permits verifying the presence of airway obstruction and determining its reversibility. Lung diffusing capacity for carbon monoxide (DLCO) is useful to define the presence of hyperinflation in obstructive disease, the presence of restrictive conditions, and to assess any alterations of the alveolar-to-capillary membrane. Cardiopulmonary exercise testing (CPET) is the gold standard in defining an aerobic exercise plan during cardiac rehabilitation in children and adults. Furthermore, its application in patients with dyspnoea is useful in distinguishing between cardiac and/or pulmonary affections. The application of other strategies, such asforced oscillation technique (FOT), could be more comfortable and require lower efforts compared to spirometry and DLCO, permitting to obtain respiratory functional data in individuals who are unable to perform a maximal forced expiratory maneuver.