This study investigates the changes in plasma cytokines and chemokines in 20 patients diagnosed with Severe Acute Respiratory Syndrome (SARS). The results show that SARS patients exhibit a significant elevation of Th1 cytokine interferon (IFN)-γ, inflammatory cytokines interleukin (IL)-1, IL-6, and IL-12 for at least 2 weeks after disease onset. However, there is no significant elevation of inflammatory cytokine tumor necrosis factor (TNF)-α, anti-inflammatory cytokine IL-10, Th1 cytokine IL-2, or Th2 cytokine IL-4. The chemokine profile demonstrates a significant elevation of neutrophil chemokine IL-8, monocyte chemoattractant protein-1 (MCP-1), and Th1 chemokine IFN-γ-inducible protein-10 (IP-10). Corticosteroid treatment significantly reduced IL-8, MCP-1, and IP-10 concentrations from 5 to 8 days after treatment. These findings confirm the activation of Th1 cell-mediated immunity and a hyperinflammatory response in SARS, likely due to the accumulation of monocytes/macrophages and neutrophils. The study suggests that these cytokines and chemokines play important roles in the immunopathological mechanisms of SARS and may serve as markers for disease severity.This study investigates the changes in plasma cytokines and chemokines in 20 patients diagnosed with Severe Acute Respiratory Syndrome (SARS). The results show that SARS patients exhibit a significant elevation of Th1 cytokine interferon (IFN)-γ, inflammatory cytokines interleukin (IL)-1, IL-6, and IL-12 for at least 2 weeks after disease onset. However, there is no significant elevation of inflammatory cytokine tumor necrosis factor (TNF)-α, anti-inflammatory cytokine IL-10, Th1 cytokine IL-2, or Th2 cytokine IL-4. The chemokine profile demonstrates a significant elevation of neutrophil chemokine IL-8, monocyte chemoattractant protein-1 (MCP-1), and Th1 chemokine IFN-γ-inducible protein-10 (IP-10). Corticosteroid treatment significantly reduced IL-8, MCP-1, and IP-10 concentrations from 5 to 8 days after treatment. These findings confirm the activation of Th1 cell-mediated immunity and a hyperinflammatory response in SARS, likely due to the accumulation of monocytes/macrophages and neutrophils. The study suggests that these cytokines and chemokines play important roles in the immunopathological mechanisms of SARS and may serve as markers for disease severity.