['The aim of this study was to assess the relationship between protein C levels and temporal changes in organ dysfunction.', 'Using data from the placebo arm of Recombinant Human Activated PROtein C Worldwide Evaluation in Severe Sepsis trial (N = 775), we compared the development of organ dysfunction over time, in adult severe sepsis patients with and without severe protein C deficiency.', 'At study enrollment (baseline), patients with and without severe protein C deficiency were similar in age and likelihood of comorbidities. Patients with severe protein C deficiency had lower arterial blood pressure (P = .0006), greater serum creatinine concentration (P < .0001), elevated markers of thrombosis and inflammation, and impairment of fibrinolysis (P < .0001). The baseline PaO(2)/FiO(2) ratio was not significantly different between the 2 groups. Seven days after study enrollment, cardiovascular and renal function remained significantly worse in patients with severe protein C deficiency (P < .0001), and respiratory dysfunction was greater (P < .0001). Baseline protein C deficiency was seen to be associated with subsequent pulmonary, renal, and hematologic organ failure.'] Is severe protein C deficiency associated with organ dysfunction in patients with severe sepsis?