Cardiac surgery in patients with chronic pulmonary diseases carries a high risk of postoperative pulmonary complications (ppc) because both are known to cause ppc. Autopsy studies have revealed ppc as the main cause of mortality in approximately 5-8% of patients after cardiac surgery. Not all pulmonary diseases are high risk comorbidities in cardiac surgery: whereas chronic obstructive pulmonary disease (COPD) and obstructive sleep apnea significantly increase the risk of ppc, a well controlled asthma does not carry an additional risk of ppc. A thorough preoperative risk stratification is crucial for risk estimation and some validated risk calculators, such as the Canet risk score exist. Surprisingly the additional value of pulmonary function testing beyond a thorough patient history and physical examination is low. No validated thresholds exist in pulmonary function testing below which cardiac surgery should be denied if clearly indicated. Perioperative strategies for risk reduction should be applied to all patients whenever possible.