The purpose is to determine the incidence of HIT in patients operated for chronic rheumatic heart disease and to evaluate the possibility of use of new test systems for diagnosis of HIT. Material and methods: In 2013 heparin-induced thrombocytopenia has been diagnosed in 17 patients operated for chronic rheumatic heart disease using immunochromatography to identify immunoglobulins G to heparin — 4 platelet factor complexes. In 2014 HIT was observed in 14 patients. In 2013 HIT developed in 2 patients after cardiac surgery on background of low-molecular heparin administration, in 2014 — in 1. Patients who were treated using heparin had complicated course of heparin-induced thrombocytopenia (venous and arterial thromboses). Our results are similar to literature data. Conclusion. Kits for qualitative detection of immunoglobulins G to heparin — 4 platelet factor complexes by using of immunochromatography allow to diagnose heparin-induced thrombocytopenia in cardiac patients in early postoperative period; does not require special expensive laboratory equipment and consumables, annual maintenance of laboratory equipment, calibration and testing, specialized training of specialists of laboratories; give the results in 15—20 minutes to determine following treatment strategy of cardiac patients.