In patients undergoing open-heart surgery pulmonary functions can be deranged by primary cardiac disorders, associated chronic pulmonary disease, as well as by other factors, such as obesity and smoking. Cardiac surgery involves a complex of several factors adversely affecting pulmonary functions, i.e. the cardiosurgical procedure itself, extracorporeal circulation, anesthesia, postoperative pain, delayed chest physiotherapy, immobilization of the patient. There is a direct correlation between pulmonary functions and postoperative pulmonary complications. The paper analyzes postoperative pulmonary complications and their causes, as well as possibilities of identifying of the patients at risk, and it evaluates the value of pulmonary function testing in this process. The possibilities of prophylaxis and prevention of pulmonary complications in the preoperative, peroperative, and postoperative period are surveyed.