It is imperative to maintain normal blood fl ow to provide adequate oxygen supply to specifi c organs and cells, as well as for the removal of metabolic byproducts. Therefore, any situation that results in blood clotting can injure or kill living tissues. In this paper, we describe a case where a protein C defi cient subject who would, by all medical indicators, be at 100 % risk of experiencing thrombophlebitis, deep vein thrombosis, and or lung emboli, is able to escape all pathologies by using perioperative zymogen protein C (ZPC). This protein C defi cient patient has a long history of blood clotting, particularly from surgical procedures. The patient is 81 years old and fi rst experienced clotting due to hernia surgery in 1964, when he was hospitalized for 16 days post-surgery with life threatening complications. It was later determined in 1980, after many episodes, that the patient had hereditary protein C defi ciency at the 38 % level. In his hernia surgery, perioperative ZPC was used along with accepted anticoagulation procedures with no blood clots or other related side effects occurring. This procedure can greatly benefi t protein C defi cient patients, and could potentially fi nd use for non-PC defi cient patients in surgeries and a variety of other medical treatments. This particular case helps to validate the importance of ZPC in effecting safer surgery in high-risk patients. It also supports the mechanism of ZPC acting as an anticoagulant without causing bleeding. Most importantly, each clinical case study represents a unique combination of surgeon, hematologist, medical staff, and patient functioning as a coordinated team. In this case, smaller amounts of very expensive ZPC achieved safe and effi cacious results, which is hugely important for future clinical applications when considering the production cost of ZPC. More studies must be done to establish minimum dosing while achieving safe and effi cacious outcomes.