Aim. To study prevention, diagnostics and treatment of postoperative chylothorax. Material and methods. For the period 2004—2014 thirty seven patients with postoperative chylothorax have been treated. Aneurysmectomy with aortic replacement were performed in 6 patients. 8 patients underwent coronary artery bypass grafting, 3 patients — heart valve replacement and 2 patients — carotid artery reconstruction. Postoperatively left-sided and right-sided chylothorax was diagnosed in 10 and 7 cases respectively. 2 patients had chylorrhea into soft tissues of the neck. The diagnosis of chylorrhea was established within 1 day—4.5 months. Treatment was started from conservative therapy, pleural drainage and hunger with total parenteral nutrition. Conservative therapy had a good clinical effect in 17 of 19 patients. Only 2 patients required surgery. They were after aortic replacement and mitral valve replacement. Thoracic duct ligation via right-sided thoracotomy was performed. Conclusion. At present time topicality of postoperative chylothorax is increased in view of development of cardiac surgery and great number of thoracic interventions. Thus, prevention and treatment of this complication should be improved. Diagnosis is based on laboratory studies and detection of neutral fat in pleural drainage. Other indicators including hypolipoproteinaemia and immune deficiency reflect the severity of disease. Pleural cavity drainage, hunger with total parenteral nutrition, medical blocking of chyle production are peferred in treatment of chylothorax. Surgery is indicated in case of massive loss of chyle or if therapy is ineffective during the first 2 weeks.