The aim of the study is to investigate whether the presence of a protein Z polymorphism is a risk factor for the development and outcome of sepsis. Sepsis is a clinical syndrome characterized by the presence of systemic signs and symptoms of inflammation. When sepsis leads to organ failure, the term severe sepsis and septic shock is used. The genetic causes of severe sepsis are not fully explained. Protein Z is a vitamin K- dependent glycoprotein and a member of the coagulation cascade. The study included 53 patients with severe sepsis and 70 control healthy volunteers without a familial history of thrombosis. The G79A polymorphism of intron F of the protein Z gene was analyzed by the method of polymerase chain reaction-based DNA analysis. The protein Z intron F G79A polymorphism frequencies of the patients and controls were 43.4% and 40%, respectively. Carrying 79 AA genotype could be a risk factor for severe sepsis and septic shock (OR = 4.5, 95% CI: 0.45-46.1), but it could not find any difference between survivor and nonsurvivor groups. They concluded that the frequency of intron F G79A polymorphism of protein Z gene was higher in patients than controls, and carrying 79 AA genotype could be a risk factor for severe sepsis and septic shock.