In an effort to better understand the interaction between the different mediators, the investigators propose to examine the time course of mediators, the indexes of organ injury and the coagulation cascade.

All patients admitted to the ICU (Including VA Medical Center, University Hospital and Presbyterian hospital) will be screened for enrollment in the study. Patients who have the diagnosis of sepsis will be asked to volunteer. We will match sepsis patients with other ICU patients without the diagnosis of sepsis. The latter will also be asked to volunteer.

Patients will be stratified into three groups:

• Sepsis
• SIRS of non-septic origin
• Other ICU patients

Routine laboratory data and clinical data (see flow sheet) will be collected. The plasma or serum will be frozen separately until the target number of patients is met. Measurements of inflammatory mediators and other cytokines/injury markers will be carried out at that point.

Inclusion Criteria:

• Admission to the ICU

Exclusion Criteria:

• No blood draws scheduled
• Hemoglobin level < 6.5 gm/dl

Patients admitted to the ICU with suspected or proven sepsis.