Pro- and anti-inflammatory cytokines, such as interferon (IFN)-γ, interleukin (IL)-6, IL-10, IL-12 and transforming growth factor (TGF)-β1, have been shown to be mediators associated with severe community-acquired pneumonia (CAP). It is unknown whether plasma TGF-β1 level can help physicians to judge disease severity. In this study, we investigated the value of predicting mortality in patients with severe CAP by the plasma levels of IFN-γ, IL-6, IL-10, IL-12 and TGF-β1 on admission day. Methods: Patients who were admitted to the emergency department and soon transferred to the ICU because of severe CAP were enrolled in this study. Plasma levels of IFN-γ, IL-6, IL-10, IL-12 and TGF-β1 on the day of admission were determined in 49 survivors and 14 non-survivors within 28 days by ELISA. Clinical characteristics were also recorded. Results: Plasma IL-6, IL-10 and TGF-β1 levels on admission were significantly different between survivors and non-survivors. Conversely, there was no significant difference in plasma IFN-γ and IL-12 levels between the survivors and non-survivors. Furthermore, the plasma TGF-β1 level was the only independent factor associated with mortality. The value of predicting mortality in patients with severe CAP was similar for IL-6, IL-10 and TGF-β1. Plasma IL-6 level was not related to the Acute Physiology and Chronic Health Evaluation (APACHE) II score. However, plasma IL-10 and TGF-β1 levels were correlated with APACHE II score. Conclusion: A severity scoring system, including TGF-β1 level on admission, may be considered as a useful parameter to predict outcomes of patients with severe CAP.