Background: The object of this study was to evaluate biomarkers for diagnosis of sepsis, hematologic parameters, and cytokine profiles for use in the diagnosis and evaluation of severity of sepsis. Methods: We enrolled 127 consecutive patients with systemic inflammatory response syndrome (SIRS), 97 of whom were diagnosed with sepsis. The following biomarkers were evaluated: procalcitonin (PCT); C-reactive protein (CRP); erythrocyte sedimentation rate (ESR); white blood cell count, immature granulocyte (IG) count; and multiplex cytokines, including interleukin (IL)1-β (IL1β), IL2, IL4, IL5, IL6, IL9, IL10, IL12p70, IL13, IL17, IL22, tumor necrosis factor-α (TNFα), and interferon-γ (IFNγ). A cytokine bead immunoassay was used to perform simultaneous measurements. Results: The disease involving urinary and respiratory tract constituted 57.5% of all patients. The severity of infection was classified as follows: SIRS patients, n=30; sepsis patients, n=81; and septic shock/severe sepsis patients, n=16. PCT, IL6, and CRP had high area under receiver operation characteristic curve (AUCs) and accuracy, which is as follows: PCT: 0.841, 80.5%; IL6: 0.811, 77.1%; CRP: 0.784, 73.8%, respectively. Severity of sepsis could be discriminated by PCT, IL6, and IL5. Unlike other cytokines, IFNγ had an inverse relation with severity of sepsis. The relationship between cytokine profiles and clinical diagnosis of sepsis was unclear. Conclusions: PCT, IL6, and CRP values could assist diagnosis, and PCT, IL6, and IL5 had discriminative properties for determination of severity of sepsis. IFNγ revealed a distinct inverse relationship with severity of sepsis. As there was no relationship between cytokine profiles and sepsis, further studies are required to develop clinical applications.