Hepar in Associated Thrombocytopenia (HAT) is a well-described clinical entity (1–5), frequently requiring prompt cessation of heparin therapy to correct the thrombocytopenia. Previously recommended management also called for discontinuing heparin for several weeks to allow the alteration in platelet aggregation to normalize prior to the safe readministration of heparin. Discontinuation of heparin presents a challenging clinical problem in patients who have developed HAT and subsequently require urgent cardiac surgery. The case report describes the use of plasmapheresis to rapidly reverse the immunologie abnormality reportedly responsible for HAT, permitting the early use of heparin in a patient with HAT who required urgent cardiac surgery.