A 74-year-old man underwent elective coronary surgery under cardiopulmonary bypass. A few minutes after the protamine administration was started, he suddenly developed a severe hypotension necessitating cardiac massage and recannulation for pump assistance. A further test dose of protamine provoked an identical reaction. We installed a Heparin Removal Device, which allows for ex-vivo deheparinization. In 35 minutes ACT decreased from 480 sec to 180 sec and clots appeared in the operating field. This system provides an excellent alternative to protamine in patients with an adverse reaction to protamine.